From cf719bca8031d935ad71f5c1cd91c8b5239cd9bb Mon Sep 17 00:00:00 2001
From: "Jonathan H. Wage" <jonwage@gmail.com>
Date: Tue, 28 May 2019 11:11:44 -0500
Subject: [PATCH] Add proper types to Doctrine\DBAL\Schema namespace.

---
 UPGRADE.md                                    |  12 +
 .../SchemaCreateTableColumnEventArgs.php      |   9 +-
 .../DBAL/Event/SchemaCreateTableEventArgs.php |   7 +-
 .../DBAL/Exception/DatabaseRequired.php       |  21 +
 .../DBAL/Id/TableGeneratorSchemaVisitor.php   |  12 +-
 .../DBAL/Platforms/AbstractPlatform.php       |  10 +-
 lib/Doctrine/DBAL/Platforms/DB2Platform.php   |   2 +-
 lib/Doctrine/DBAL/Platforms/MySqlPlatform.php |   4 +-
 .../DBAL/Platforms/OraclePlatform.php         |   4 +-
 .../DBAL/Platforms/PostgreSqlPlatform.php     |   2 +-
 .../DBAL/Platforms/SQLAnywherePlatform.php    |   2 +-
 .../DBAL/Platforms/SQLServerPlatform.php      |   2 +-
 .../DBAL/Platforms/SqlitePlatform.php         |   6 +-
 lib/Doctrine/DBAL/Schema/AbstractAsset.php    |  60 +--
 .../DBAL/Schema/AbstractSchemaManager.php     | 410 +++++++-----------
 lib/Doctrine/DBAL/Schema/Column.php           |  18 +-
 lib/Doctrine/DBAL/Schema/ColumnDiff.php       |  19 +-
 lib/Doctrine/DBAL/Schema/Comparator.php       |  51 +--
 lib/Doctrine/DBAL/Schema/Constraint.php       |  18 +-
 lib/Doctrine/DBAL/Schema/DB2SchemaManager.php |  12 +-
 .../DBAL/Schema/ForeignKeyConstraint.php      | 111 ++---
 lib/Doctrine/DBAL/Schema/Identifier.php       |   2 +-
 lib/Doctrine/DBAL/Schema/Index.php            | 119 ++---
 .../DBAL/Schema/MySqlSchemaManager.php        |  19 +-
 .../DBAL/Schema/OracleSchemaManager.php       |  53 +--
 .../DBAL/Schema/PostgreSqlSchemaManager.php   |  42 +-
 .../DBAL/Schema/SQLAnywhereSchemaManager.php  |  32 +-
 .../DBAL/Schema/SQLServerSchemaManager.php    |  40 +-
 lib/Doctrine/DBAL/Schema/Schema.php           | 147 ++-----
 lib/Doctrine/DBAL/Schema/SchemaConfig.php     |  52 +--
 lib/Doctrine/DBAL/Schema/SchemaDiff.php       |  40 +-
 lib/Doctrine/DBAL/Schema/Sequence.php         |  57 +--
 .../DBAL/Schema/SqliteSchemaManager.php       |  94 ++--
 .../AbstractSchemaSynchronizer.php            |   8 +-
 .../Synchronizer/SchemaSynchronizer.php       |  34 +-
 .../SingleDatabaseSynchronizer.php            |  16 +-
 lib/Doctrine/DBAL/Schema/Table.php            | 278 ++++--------
 lib/Doctrine/DBAL/Schema/TableDiff.php        |  66 ++-
 lib/Doctrine/DBAL/Schema/UniqueConstraint.php |  62 +--
 lib/Doctrine/DBAL/Schema/View.php             |  11 +-
 .../DBAL/Schema/Visitor/AbstractVisitor.php   |  14 +-
 .../Visitor/CreateSchemaSqlCollector.php      |  25 +-
 .../Schema/Visitor/DropSchemaSqlCollector.php |  15 +-
 lib/Doctrine/DBAL/Schema/Visitor/Graphviz.php |  36 +-
 .../DBAL/Schema/Visitor/NamespaceVisitor.php  |   2 +-
 .../Schema/Visitor/RemoveNamespacedAssets.php |   8 +-
 lib/Doctrine/DBAL/Schema/Visitor/Visitor.php  |  40 +-
 .../SQLAzureFederationsSynchronizer.php       |  16 +-
 .../SQLAzure/Schema/MultiTenantVisitor.php    |  12 +-
 .../Driver/PDOSqlite/DriverTest.php           |   5 +
 .../DBAL/Functional/NamedParametersTest.php   |   2 +-
 .../DBAL/Functional/Schema/ComparatorTest.php |   2 +-
 .../Schema/MySqlSchemaManagerTest.php         |  25 +-
 .../Schema/PostgreSqlSchemaManagerTest.php    |   6 +-
 .../SchemaManagerFunctionalTestCase.php       |   4 +-
 .../Schema/SqliteSchemaManagerTest.php        |   2 +-
 .../DBAL/Functional/Ticket/DBAL202Test.php    |   2 +-
 .../DBAL/Functional/Ticket/DBAL510Test.php    |   2 +-
 .../Tests/DBAL/Schema/ComparatorTest.php      |   6 +-
 .../Tests/DBAL/Schema/TableDiffTest.php       |   2 +-
 60 files changed, 791 insertions(+), 1399 deletions(-)
 create mode 100644 lib/Doctrine/DBAL/Exception/DatabaseRequired.php

diff --git a/UPGRADE.md b/UPGRADE.md
index fd85577aaf5..656239fddcc 100644
--- a/UPGRADE.md
+++ b/UPGRADE.md
@@ -1,5 +1,17 @@
 # Upgrade to 3.0
 
+## BC BREAK: Changes in the `Doctrine\DBAL\Schema` API
+
+- Method `Doctrine\DBAL\Schema\AbstractSchemaManager::_getPortableViewDefinition()` no longer optionally returns false. It will always return a `Doctrine\DBAL\Schema\View` instance.
+- Method `Doctrine\DBAL\Schema\Comparator::diffTable()` now optionally returns null instead of false.
+- Property `Doctrine\DBAL\Schema\TableDiff::$newName` is now optionally null instead of false.
+- Method `Doctrine\DBAL\Schema\AbstractSchemaManager::tablesExist()` no longer accepts a string. Use `Doctrine\DBAL\Schema\AbstractSchemaManager::tableExists()` instead.
+- Method `Doctrine\DBAL\Schema\OracleSchemaManager::createDatabase()` no longer accepts `null` for `$database` argument.
+- Removed unused method `Doctrine\DBAL\Schema\AbstractSchemaManager::_getPortableFunctionsList()`
+- Removed unused method `Doctrine\DBAL\Schema\AbstractSchemaManager::_getPortableFunctionDefinition()`
+- Removed unused method `Doctrine\DBAL\Schema\OracleSchemaManager::_getPortableFunctionDefinition()`
+- Removed unused method `Doctrine\DBAL\Schema\SqliteSchemaManager::_getPortableTableIndexDefinition()`
+
 ## BC BREAK: Changes in the `Doctrine\DBAL\Driver` API
 
 1. The `$username` and `$password` arguments of `::connect()` are no longer nullable. Use an empty string to indicate empty username or password.
diff --git a/lib/Doctrine/DBAL/Event/SchemaCreateTableColumnEventArgs.php b/lib/Doctrine/DBAL/Event/SchemaCreateTableColumnEventArgs.php
index 312892daa7b..f4e70e0ff89 100644
--- a/lib/Doctrine/DBAL/Event/SchemaCreateTableColumnEventArgs.php
+++ b/lib/Doctrine/DBAL/Event/SchemaCreateTableColumnEventArgs.php
@@ -7,7 +7,6 @@
 use Doctrine\DBAL\Platforms\AbstractPlatform;
 use Doctrine\DBAL\Schema\Column;
 use Doctrine\DBAL\Schema\Table;
-use function array_merge;
 use function is_array;
 
 /**
@@ -24,7 +23,7 @@ class SchemaCreateTableColumnEventArgs extends SchemaEventArgs
     /** @var AbstractPlatform */
     private $platform;
 
-    /** @var string[] */
+    /** @var array<int, string> */
     private $sql = [];
 
     public function __construct(Column $column, Table $table, AbstractPlatform $platform)
@@ -66,7 +65,9 @@ public function getPlatform()
     public function addSql($sql)
     {
         if (is_array($sql)) {
-            $this->sql = array_merge($this->sql, $sql);
+            foreach ($sql as $query) {
+                $this->sql[] = $query;
+            }
         } else {
             $this->sql[] = $sql;
         }
@@ -75,7 +76,7 @@ public function addSql($sql)
     }
 
     /**
-     * @return string[]
+     * @return array<int, string>
      */
     public function getSql()
     {
diff --git a/lib/Doctrine/DBAL/Event/SchemaCreateTableEventArgs.php b/lib/Doctrine/DBAL/Event/SchemaCreateTableEventArgs.php
index 7c05d1e8df1..5046add54c3 100644
--- a/lib/Doctrine/DBAL/Event/SchemaCreateTableEventArgs.php
+++ b/lib/Doctrine/DBAL/Event/SchemaCreateTableEventArgs.php
@@ -6,7 +6,6 @@
 
 use Doctrine\DBAL\Platforms\AbstractPlatform;
 use Doctrine\DBAL\Schema\Table;
-use function array_merge;
 use function is_array;
 
 /**
@@ -81,7 +80,9 @@ public function getPlatform()
     public function addSql($sql)
     {
         if (is_array($sql)) {
-            $this->sql = array_merge($this->sql, $sql);
+            foreach ($sql as $query) {
+                $this->sql[] = $query;
+            }
         } else {
             $this->sql[] = $sql;
         }
@@ -90,7 +91,7 @@ public function addSql($sql)
     }
 
     /**
-     * @return string[]
+     * @return array<int, string>
      */
     public function getSql()
     {
diff --git a/lib/Doctrine/DBAL/Exception/DatabaseRequired.php b/lib/Doctrine/DBAL/Exception/DatabaseRequired.php
new file mode 100644
index 00000000000..b2110e5339e
--- /dev/null
+++ b/lib/Doctrine/DBAL/Exception/DatabaseRequired.php
@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\DBAL\Exception;
+
+use Doctrine\DBAL\DBALException;
+use function sprintf;
+
+class DatabaseRequired extends DBALException
+{
+    public static function new(string $methodName) : self
+    {
+        return new self(
+            sprintf(
+                'A database is required for the method: %s.',
+                $methodName
+            )
+        );
+    }
+}
diff --git a/lib/Doctrine/DBAL/Id/TableGeneratorSchemaVisitor.php b/lib/Doctrine/DBAL/Id/TableGeneratorSchemaVisitor.php
index 9e2efa91b46..0ce062a9a5d 100644
--- a/lib/Doctrine/DBAL/Id/TableGeneratorSchemaVisitor.php
+++ b/lib/Doctrine/DBAL/Id/TableGeneratorSchemaVisitor.php
@@ -28,7 +28,7 @@ public function __construct($generatorTableName = 'sequences')
     /**
      * {@inheritdoc}
      */
-    public function acceptSchema(Schema $schema)
+    public function acceptSchema(Schema $schema) : void
     {
         $table = $schema->createTable($this->generatorTableName);
         $table->addColumn('sequence_name', 'string');
@@ -39,35 +39,35 @@ public function acceptSchema(Schema $schema)
     /**
      * {@inheritdoc}
      */
-    public function acceptTable(Table $table)
+    public function acceptTable(Table $table) : void
     {
     }
 
     /**
      * {@inheritdoc}
      */
-    public function acceptColumn(Table $table, Column $column)
+    public function acceptColumn(Table $table, Column $column) : void
     {
     }
 
     /**
      * {@inheritdoc}
      */
-    public function acceptForeignKey(Table $localTable, ForeignKeyConstraint $fkConstraint)
+    public function acceptForeignKey(Table $localTable, ForeignKeyConstraint $fkConstraint) : void
     {
     }
 
     /**
      * {@inheritdoc}
      */
-    public function acceptIndex(Table $table, Index $index)
+    public function acceptIndex(Table $table, Index $index) : void
     {
     }
 
     /**
      * {@inheritdoc}
      */
-    public function acceptSequence(Sequence $sequence)
+    public function acceptSequence(Sequence $sequence) : void
     {
     }
 }
diff --git a/lib/Doctrine/DBAL/Platforms/AbstractPlatform.php b/lib/Doctrine/DBAL/Platforms/AbstractPlatform.php
index 1a0223ad33d..f188220b100 100644
--- a/lib/Doctrine/DBAL/Platforms/AbstractPlatform.php
+++ b/lib/Doctrine/DBAL/Platforms/AbstractPlatform.php
@@ -1274,7 +1274,7 @@ public function getDropForeignKeySQL($foreignKey, $table) : string
      * Returns the SQL statement(s) to create a table with the specified name, columns and constraints
      * on this platform.
      *
-     * @return string[] The sequence of SQL statements.
+     * @return array<int, string> The sequence of SQL statements.
      *
      * @throws DBALException
      */
@@ -1420,7 +1420,7 @@ public function getInlineColumnCommentSQL(?string $comment) : string
      * @param mixed[][] $columns
      * @param mixed[]   $options
      *
-     * @return string[]
+     * @return array<int, string>
      */
     protected function _getCreateTableSQL(string $tableName, array $columns, array $options = []) : array
     {
@@ -1450,7 +1450,7 @@ protected function _getCreateTableSQL(string $tableName, array $columns, array $
         }
         $query .= ')';
 
-        $sql[] = $query;
+        $sql = [$query];
 
         if (isset($options['foreignKeys'])) {
             foreach ((array) $options['foreignKeys'] as $definition) {
@@ -1656,7 +1656,7 @@ public function getCreateForeignKeySQL(ForeignKeyConstraint $foreignKey, $table)
      *
      * This method returns an array of SQL statements, since some platforms need several statements.
      *
-     * @return string[]
+     * @return array<int, string>
      *
      * @throws DBALException If not supported on this platform.
      */
@@ -1805,7 +1805,7 @@ protected function getPostAlterTableIndexForeignKeySQL(TableDiff $diff) : array
         $sql     = [];
         $newName = $diff->getNewName();
 
-        if ($newName !== false) {
+        if ($newName !== null) {
             $tableName = $newName->getQuotedName($this);
         } else {
             $tableName = $diff->getName($this)->getQuotedName($this);
diff --git a/lib/Doctrine/DBAL/Platforms/DB2Platform.php b/lib/Doctrine/DBAL/Platforms/DB2Platform.php
index 0666f53c096..2c9004347b0 100644
--- a/lib/Doctrine/DBAL/Platforms/DB2Platform.php
+++ b/lib/Doctrine/DBAL/Platforms/DB2Platform.php
@@ -597,7 +597,7 @@ public function getAlterTableSQL(TableDiff $diff) : array
 
             $newName = $diff->getNewName();
 
-            if ($newName !== false) {
+            if ($newName !== null) {
                 $sql[] = sprintf(
                     'RENAME TABLE %s TO %s',
                     $diff->getName($this)->getQuotedName($this),
diff --git a/lib/Doctrine/DBAL/Platforms/MySqlPlatform.php b/lib/Doctrine/DBAL/Platforms/MySqlPlatform.php
index ffefac2e69c..b0f262ca0ce 100644
--- a/lib/Doctrine/DBAL/Platforms/MySqlPlatform.php
+++ b/lib/Doctrine/DBAL/Platforms/MySqlPlatform.php
@@ -510,7 +510,7 @@ public function getAlterTableSQL(TableDiff $diff) : array
         $queryParts = [];
         $newName    = $diff->getNewName();
 
-        if ($newName !== false) {
+        if ($newName !== null) {
             $queryParts[] = 'RENAME TO ' . $newName->getQuotedName($this);
         }
 
@@ -815,7 +815,7 @@ protected function getPostAlterTableRenameIndexForeignKeySQL(TableDiff $diff) :
         $sql     = [];
         $newName = $diff->getNewName();
 
-        if ($newName !== false) {
+        if ($newName !== null) {
             $tableName = $newName->getQuotedName($this);
         } else {
             $tableName = $diff->getName($this)->getQuotedName($this);
diff --git a/lib/Doctrine/DBAL/Platforms/OraclePlatform.php b/lib/Doctrine/DBAL/Platforms/OraclePlatform.php
index dd246fe1eb3..a763a04c966 100644
--- a/lib/Doctrine/DBAL/Platforms/OraclePlatform.php
+++ b/lib/Doctrine/DBAL/Platforms/OraclePlatform.php
@@ -461,7 +461,7 @@ public function getDropViewSQL(string $name) : string
     }
 
     /**
-     * @return string[]
+     * @return array<int, string>
      */
     public function getCreateAutoincrementSql(string $name, string $table, int $start = 1) : array
     {
@@ -854,7 +854,7 @@ public function getAlterTableSQL(TableDiff $diff) : array
 
             $newName = $diff->getNewName();
 
-            if ($newName !== false) {
+            if ($newName !== null) {
                 $sql[] = sprintf(
                     'ALTER TABLE %s RENAME TO %s',
                     $diff->getName($this)->getQuotedName($this),
diff --git a/lib/Doctrine/DBAL/Platforms/PostgreSqlPlatform.php b/lib/Doctrine/DBAL/Platforms/PostgreSqlPlatform.php
index d86a302a3ab..43b44ab3ecb 100644
--- a/lib/Doctrine/DBAL/Platforms/PostgreSqlPlatform.php
+++ b/lib/Doctrine/DBAL/Platforms/PostgreSqlPlatform.php
@@ -591,7 +591,7 @@ public function getAlterTableSQL(TableDiff $diff) : array
 
             $newName = $diff->getNewName();
 
-            if ($newName !== false) {
+            if ($newName !== null) {
                 $sql[] = sprintf(
                     'ALTER TABLE %s RENAME TO %s',
                     $diff->getName($this)->getQuotedName($this),
diff --git a/lib/Doctrine/DBAL/Platforms/SQLAnywherePlatform.php b/lib/Doctrine/DBAL/Platforms/SQLAnywherePlatform.php
index b3f370cc4e4..4b1d949a3e6 100644
--- a/lib/Doctrine/DBAL/Platforms/SQLAnywherePlatform.php
+++ b/lib/Doctrine/DBAL/Platforms/SQLAnywherePlatform.php
@@ -190,7 +190,7 @@ public function getAlterTableSQL(TableDiff $diff) : array
 
             $newName = $diff->getNewName();
 
-            if ($newName !== false) {
+            if ($newName !== null) {
                 $sql[] = $this->getAlterTableClause($diff->getName($this)) . ' ' .
                     $this->getAlterTableRenameTableClause($newName);
             }
diff --git a/lib/Doctrine/DBAL/Platforms/SQLServerPlatform.php b/lib/Doctrine/DBAL/Platforms/SQLServerPlatform.php
index ad2a4ad20a3..9462504fec2 100644
--- a/lib/Doctrine/DBAL/Platforms/SQLServerPlatform.php
+++ b/lib/Doctrine/DBAL/Platforms/SQLServerPlatform.php
@@ -579,7 +579,7 @@ public function getAlterTableSQL(TableDiff $diff) : array
 
         $newName = $diff->getNewName();
 
-        if ($newName !== false) {
+        if ($newName !== null) {
             $sql[] = "sp_RENAME '" . $diff->getName($this)->getQuotedName($this) . "', '" . $newName->getName() . "'";
 
             /**
diff --git a/lib/Doctrine/DBAL/Platforms/SqlitePlatform.php b/lib/Doctrine/DBAL/Platforms/SqlitePlatform.php
index ee35409bdd6..689fd47ab72 100644
--- a/lib/Doctrine/DBAL/Platforms/SqlitePlatform.php
+++ b/lib/Doctrine/DBAL/Platforms/SqlitePlatform.php
@@ -684,7 +684,7 @@ protected function getPostAlterTableIndexForeignKeySQL(TableDiff $diff) : array
         $sql       = [];
         $tableName = $diff->getNewName();
 
-        if ($tableName === false) {
+        if ($tableName === null) {
             $tableName = $diff->getName($this);
         }
 
@@ -911,7 +911,7 @@ public function getAlterTableSQL(TableDiff $diff) : array
 
             $newName = $diff->getNewName();
 
-            if ($newName !== false) {
+            if ($newName !== null) {
                 $sql[] = sprintf(
                     'ALTER TABLE %s RENAME TO %s',
                     $newTable->getQuotedName($this),
@@ -993,7 +993,7 @@ private function getSimpleAlterTableSQL(TableDiff $diff)
         }
 
         if (! $this->onSchemaAlterTable($diff, $tableSql)) {
-            if ($diff->newName !== false) {
+            if ($diff->newName !== null) {
                 $newTable = new Identifier($diff->newName);
                 $sql[]    = 'ALTER TABLE ' . $table->getQuotedName($this) . ' RENAME TO ' . $newTable->getQuotedName($this);
             }
diff --git a/lib/Doctrine/DBAL/Schema/AbstractAsset.php b/lib/Doctrine/DBAL/Schema/AbstractAsset.php
index cfa469d9de7..6afec63d20d 100644
--- a/lib/Doctrine/DBAL/Schema/AbstractAsset.php
+++ b/lib/Doctrine/DBAL/Schema/AbstractAsset.php
@@ -39,12 +39,8 @@ abstract class AbstractAsset
 
     /**
      * Sets the name of this asset.
-     *
-     * @param string $name
-     *
-     * @return void
      */
-    protected function _setName($name)
+    protected function _setName(string $name) : void
     {
         if ($this->isIdentifierQuoted($name)) {
             $this->_quoted = true;
@@ -60,12 +56,8 @@ protected function _setName($name)
 
     /**
      * Is this asset in the default namespace?
-     *
-     * @param string $defaultNamespaceName
-     *
-     * @return bool
      */
-    public function isInDefaultNamespace($defaultNamespaceName)
+    public function isInDefaultNamespace(string $defaultNamespaceName) : bool
     {
         return $this->_namespace === $defaultNamespaceName || $this->_namespace === null;
     }
@@ -74,10 +66,8 @@ public function isInDefaultNamespace($defaultNamespaceName)
      * Gets the namespace name of this asset.
      *
      * If NULL is returned this means the default namespace is used.
-     *
-     * @return string|null
      */
-    public function getNamespaceName()
+    public function getNamespaceName() : ?string
     {
         return $this->_namespace;
     }
@@ -85,12 +75,8 @@ public function getNamespaceName()
     /**
      * The shortest name is stripped of the default namespace. All other
      * namespaced elements are returned as full-qualified names.
-     *
-     * @param string|null $defaultNamespaceName
-     *
-     * @return string
      */
-    public function getShortestName($defaultNamespaceName)
+    public function getShortestName(?string $defaultNamespaceName) : string
     {
         $shortestName = $this->getName();
         if ($this->_namespace === $defaultNamespaceName) {
@@ -108,12 +94,8 @@ public function getShortestName($defaultNamespaceName)
      *
      * Every non-namespaced element is prefixed with the default namespace
      * name which is passed as argument to this method.
-     *
-     * @param string $defaultNamespaceName
-     *
-     * @return string
      */
-    public function getFullQualifiedName($defaultNamespaceName)
+    public function getFullQualifiedName(string $defaultNamespaceName) : string
     {
         $name = $this->getName();
         if (! $this->_namespace) {
@@ -125,44 +107,32 @@ public function getFullQualifiedName($defaultNamespaceName)
 
     /**
      * Checks if this asset's name is quoted.
-     *
-     * @return bool
      */
-    public function isQuoted()
+    public function isQuoted() : bool
     {
         return $this->_quoted;
     }
 
     /**
      * Checks if this identifier is quoted.
-     *
-     * @param string $identifier
-     *
-     * @return bool
      */
-    protected function isIdentifierQuoted($identifier)
+    protected function isIdentifierQuoted(string $identifier) : bool
     {
         return isset($identifier[0]) && ($identifier[0] === '`' || $identifier[0] === '"' || $identifier[0] === '[');
     }
 
     /**
      * Trim quotes from the identifier.
-     *
-     * @param string $identifier
-     *
-     * @return string
      */
-    protected function trimQuotes($identifier)
+    protected function trimQuotes(string $identifier) : string
     {
         return str_replace(['`', '"', '[', ']'], '', $identifier);
     }
 
     /**
      * Returns the name of this schema asset.
-     *
-     * @return string
      */
-    public function getName()
+    public function getName() : string
     {
         if ($this->_namespace) {
             return $this->_namespace . '.' . $this->_name;
@@ -174,10 +144,8 @@ public function getName()
     /**
      * Gets the quoted representation of this asset but only if it was defined with one. Otherwise
      * return the plain unquoted value as inserted.
-     *
-     * @return string
      */
-    public function getQuotedName(AbstractPlatform $platform)
+    public function getQuotedName(AbstractPlatform $platform) : string
     {
         $keywords = $platform->getReservedKeywordsList();
         $parts    = explode('.', $this->getName());
@@ -195,13 +163,9 @@ public function getQuotedName(AbstractPlatform $platform)
      * however building idents automatically for foreign keys, composite keys or such can easily create
      * very long names.
      *
-     * @param string[] $columnNames
-     * @param string   $prefix
-     * @param int      $maxSize
-     *
-     * @return string
+     * @param array<int, string> $columnNames
      */
-    protected function _generateIdentifierName($columnNames, $prefix = '', $maxSize = 30)
+    protected function _generateIdentifierName(array $columnNames, string $prefix = '', int $maxSize = 30) : string
     {
         $hash = implode('', array_map(static function ($column) {
             return dechex(crc32($column));
diff --git a/lib/Doctrine/DBAL/Schema/AbstractSchemaManager.php b/lib/Doctrine/DBAL/Schema/AbstractSchemaManager.php
index b97b8155014..2261b9c5f24 100644
--- a/lib/Doctrine/DBAL/Schema/AbstractSchemaManager.php
+++ b/lib/Doctrine/DBAL/Schema/AbstractSchemaManager.php
@@ -10,12 +10,14 @@
 use Doctrine\DBAL\Event\SchemaColumnDefinitionEventArgs;
 use Doctrine\DBAL\Event\SchemaIndexDefinitionEventArgs;
 use Doctrine\DBAL\Events;
+use Doctrine\DBAL\Exception\DatabaseRequired;
 use Doctrine\DBAL\Platforms\AbstractPlatform;
 use Doctrine\DBAL\Platforms\Exception\NotSupported;
 use Throwable;
 use function array_filter;
 use function array_intersect;
 use function array_map;
+use function array_shift;
 use function array_values;
 use function assert;
 use function call_user_func_array;
@@ -57,10 +59,8 @@ public function __construct(Connection $conn, ?AbstractPlatform $platform = null
 
     /**
      * Returns the associated platform.
-     *
-     * @return AbstractPlatform
      */
-    public function getDatabasePlatform()
+    public function getDatabasePlatform() : AbstractPlatform
     {
         return $this->_platform;
     }
@@ -97,9 +97,9 @@ public function tryMethod()
     /**
      * Lists the available databases for this connection.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function listDatabases()
+    public function listDatabases() : array
     {
         $sql = $this->_platform->getListDatabasesSQL();
 
@@ -111,9 +111,9 @@ public function listDatabases()
     /**
      * Returns a list of all namespaces in the current database.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function listNamespaceNames()
+    public function listNamespaceNames() : array
     {
         $sql = $this->_platform->getListNamespacesSQL();
 
@@ -125,15 +125,15 @@ public function listNamespaceNames()
     /**
      * Lists the available sequences for this connection.
      *
-     * @param string|null $database
-     *
-     * @return Sequence[]
+     * @return array<int, Sequence>
      */
-    public function listSequences($database = null)
+    public function listSequences(?string $database = null) : array
     {
-        if ($database === null) {
-            $database = $this->_conn->getDatabase();
-        }
+        $database = $this->ensureDatabase(
+            $database ?? $this->_conn->getDatabase(),
+            __METHOD__
+        );
+
         $sql = $this->_platform->getListSequencesSQL($database);
 
         $sequences = $this->_conn->fetchAll($sql);
@@ -151,16 +151,14 @@ public function listSequences($database = null)
      * of a table. Where a RDBMS specifies more details, these are held
      * in the platformDetails array.
      *
-     * @param string      $table    The name of the table.
-     * @param string|null $database
-     *
-     * @return Column[]
+     * @return array<string, Column>
      */
-    public function listTableColumns($table, $database = null)
+    public function listTableColumns(string $table, ?string $database = null) : array
     {
-        if (! $database) {
-            $database = $this->_conn->getDatabase();
-        }
+        $database = $this->ensureDatabase(
+            $database ?? $this->_conn->getDatabase(),
+            __METHOD__
+        );
 
         $sql = $this->_platform->getListTableColumnsSQL($table, $database);
 
@@ -174,11 +172,9 @@ public function listTableColumns($table, $database = null)
      *
      * Keys of the portable indexes list are all lower-cased.
      *
-     * @param string $table The name of the table.
-     *
-     * @return Index[]
+     * @return array<string, Index>
      */
-    public function listTableIndexes($table)
+    public function listTableIndexes(string $table) : array
     {
         $sql = $this->_platform->getListTableIndexesSQL($table, $this->_conn->getDatabase());
 
@@ -190,23 +186,26 @@ public function listTableIndexes($table)
     /**
      * Returns true if all the given tables exist.
      *
-     * @param string|string[] $tableNames
-     *
-     * @return bool
+     * @param array<int, string> $tableNames
      */
-    public function tablesExist($tableNames)
+    public function tablesExist(array $tableNames) : bool
     {
-        $tableNames = array_map('strtolower', (array) $tableNames);
+        $tableNames = array_map('strtolower', $tableNames);
 
         return count($tableNames) === count(array_intersect($tableNames, array_map('strtolower', $this->listTableNames())));
     }
 
+    public function tableExists(string $tableName) : bool
+    {
+        return $this->tablesExist([$tableName]);
+    }
+
     /**
      * Returns a list of all tables in the current database.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function listTableNames()
+    public function listTableNames() : array
     {
         $sql = $this->_platform->getListTablesSQL();
 
@@ -220,11 +219,11 @@ public function listTableNames()
      * Filters asset names if they are configured to return only a subset of all
      * the found elements.
      *
-     * @param mixed[] $assetNames
+     * @param array<int, mixed> $assetNames
      *
-     * @return mixed[]
+     * @return array<int, mixed>
      */
-    protected function filterAssetNames($assetNames)
+    protected function filterAssetNames(array $assetNames)
     {
         $filter = $this->_conn->getConfiguration()->getSchemaAssetsFilter();
         if (! $filter) {
@@ -237,9 +236,9 @@ protected function filterAssetNames($assetNames)
     /**
      * Lists the tables for this connection.
      *
-     * @return Table[]
+     * @return array<int, Table>
      */
-    public function listTables()
+    public function listTables() : array
     {
         $tableNames = $this->listTableNames();
 
@@ -251,12 +250,7 @@ public function listTables()
         return $tables;
     }
 
-    /**
-     * @param string $tableName
-     *
-     * @return Table
-     */
-    public function listTableDetails($tableName)
+    public function listTableDetails(string $tableName) : Table
     {
         $columns     = $this->listTableColumns($tableName);
         $foreignKeys = [];
@@ -273,13 +267,17 @@ public function listTableDetails($tableName)
     /**
      * Lists the views this connection has.
      *
-     * @return View[]
+     * @return array<string, View>
      */
-    public function listViews()
+    public function listViews() : array
     {
-        $database = $this->_conn->getDatabase();
-        $sql      = $this->_platform->getListViewsSQL($database);
-        $views    = $this->_conn->fetchAll($sql);
+        $database = $this->ensureDatabase(
+            $this->_conn->getDatabase(),
+            __METHOD__
+        );
+
+        $sql   = $this->_platform->getListViewsSQL($database);
+        $views = $this->_conn->fetchAll($sql);
 
         return $this->_getPortableViewsList($views);
     }
@@ -287,12 +285,9 @@ public function listViews()
     /**
      * Lists the foreign keys for the given table.
      *
-     * @param string      $table    The name of the table.
-     * @param string|null $database
-     *
-     * @return ForeignKeyConstraint[]
+     * @return array<int|string, ForeignKeyConstraint>
      */
-    public function listTableForeignKeys($table, $database = null)
+    public function listTableForeignKeys(string $table, ?string $database = null) : array
     {
         if ($database === null) {
             $database = $this->_conn->getDatabase();
@@ -309,24 +304,16 @@ public function listTableForeignKeys($table, $database = null)
      * Drops a database.
      *
      * NOTE: You can not drop the database this SchemaManager is currently connected to.
-     *
-     * @param string $database The name of the database to drop.
-     *
-     * @return void
      */
-    public function dropDatabase($database)
+    public function dropDatabase(string $database) : void
     {
         $this->_execSql($this->_platform->getDropDatabaseSQL($database));
     }
 
     /**
      * Drops the given table.
-     *
-     * @param string $tableName The name of the table to drop.
-     *
-     * @return void
      */
-    public function dropTable($tableName)
+    public function dropTable(string $tableName) : void
     {
         $this->_execSql($this->_platform->getDropTableSQL($tableName));
     }
@@ -336,10 +323,8 @@ public function dropTable($tableName)
      *
      * @param Index|string $index The name of the index.
      * @param Table|string $table The name of the table.
-     *
-     * @return void
      */
-    public function dropIndex($index, $table)
+    public function dropIndex($index, $table) : void
     {
         if ($index instanceof Index) {
             $index = $index->getQuotedName($this->_platform);
@@ -352,10 +337,8 @@ public function dropIndex($index, $table)
      * Drops the constraint from the given table.
      *
      * @param Table|string $table The name of the table.
-     *
-     * @return void
      */
-    public function dropConstraint(Constraint $constraint, $table)
+    public function dropConstraint(Constraint $constraint, $table) : void
     {
         $this->_execSql($this->_platform->getDropConstraintSQL($constraint, $table));
     }
@@ -365,34 +348,24 @@ public function dropConstraint(Constraint $constraint, $table)
      *
      * @param ForeignKeyConstraint|string $foreignKey The name of the foreign key.
      * @param Table|string                $table      The name of the table with the foreign key.
-     *
-     * @return void
      */
-    public function dropForeignKey($foreignKey, $table)
+    public function dropForeignKey($foreignKey, $table) : void
     {
         $this->_execSql($this->_platform->getDropForeignKeySQL($foreignKey, $table));
     }
 
     /**
      * Drops a sequence with a given name.
-     *
-     * @param string $name The name of the sequence to drop.
-     *
-     * @return void
      */
-    public function dropSequence($name)
+    public function dropSequence(string $name) : void
     {
         $this->_execSql($this->_platform->getDropSequenceSQL($name));
     }
 
     /**
      * Drops a view.
-     *
-     * @param string $name The name of the view.
-     *
-     * @return void
      */
-    public function dropView($name)
+    public function dropView(string $name) : void
     {
         $this->_execSql($this->_platform->getDropViewSQL($name));
     }
@@ -401,22 +374,16 @@ public function dropView($name)
 
     /**
      * Creates a new database.
-     *
-     * @param string $database The name of the database to create.
-     *
-     * @return void
      */
-    public function createDatabase($database)
+    public function createDatabase(string $database) : void
     {
         $this->_execSql($this->_platform->getCreateDatabaseSQL($database));
     }
 
     /**
      * Creates a new table.
-     *
-     * @return void
      */
-    public function createTable(Table $table)
+    public function createTable(Table $table) : void
     {
         $createFlags = AbstractPlatform::CREATE_INDEXES|AbstractPlatform::CREATE_FOREIGNKEYS;
         $this->_execSql($this->_platform->getCreateTableSQL($table, $createFlags));
@@ -425,13 +392,9 @@ public function createTable(Table $table)
     /**
      * Creates a new sequence.
      *
-     * @param Sequence $sequence
-     *
-     * @return void
-     *
      * @throws ConnectionException If something fails at database level.
      */
-    public function createSequence($sequence)
+    public function createSequence(Sequence $sequence) : void
     {
         $this->_execSql($this->_platform->getCreateSequenceSQL($sequence));
     }
@@ -440,10 +403,8 @@ public function createSequence($sequence)
      * Creates a constraint on a table.
      *
      * @param Table|string $table
-     *
-     * @return void
      */
-    public function createConstraint(Constraint $constraint, $table)
+    public function createConstraint(Constraint $constraint, $table) : void
     {
         $this->_execSql($this->_platform->getCreateConstraintSQL($constraint, $table));
     }
@@ -452,10 +413,8 @@ public function createConstraint(Constraint $constraint, $table)
      * Creates a new index on a table.
      *
      * @param Table|string $table The name of the table on which the index is to be created.
-     *
-     * @return void
      */
-    public function createIndex(Index $index, $table)
+    public function createIndex(Index $index, $table) : void
     {
         $this->_execSql($this->_platform->getCreateIndexSQL($index, $table));
     }
@@ -465,20 +424,16 @@ public function createIndex(Index $index, $table)
      *
      * @param ForeignKeyConstraint $foreignKey The ForeignKey instance.
      * @param Table|string         $table      The name of the table on which the foreign key is to be created.
-     *
-     * @return void
      */
-    public function createForeignKey(ForeignKeyConstraint $foreignKey, $table)
+    public function createForeignKey(ForeignKeyConstraint $foreignKey, $table) : void
     {
         $this->_execSql($this->_platform->getCreateForeignKeySQL($foreignKey, $table));
     }
 
     /**
      * Creates a new view.
-     *
-     * @return void
      */
-    public function createView(View $view)
+    public function createView(View $view) : void
     {
         $this->_execSql($this->_platform->getCreateViewSQL($view->getQuotedName($this->_platform), $view->getSql()));
     }
@@ -492,10 +447,8 @@ public function createView(View $view)
      * @see createConstraint()
      *
      * @param Table|string $table
-     *
-     * @return void
      */
-    public function dropAndCreateConstraint(Constraint $constraint, $table)
+    public function dropAndCreateConstraint(Constraint $constraint, $table) : void
     {
         $this->tryMethod('dropConstraint', $constraint, $table);
         $this->createConstraint($constraint, $table);
@@ -505,10 +458,8 @@ public function dropAndCreateConstraint(Constraint $constraint, $table)
      * Drops and creates a new index on a table.
      *
      * @param Table|string $table The name of the table on which the index is to be created.
-     *
-     * @return void
      */
-    public function dropAndCreateIndex(Index $index, $table)
+    public function dropAndCreateIndex(Index $index, $table) : void
     {
         $this->tryMethod('dropIndex', $index->getQuotedName($this->_platform), $table);
         $this->createIndex($index, $table);
@@ -519,10 +470,8 @@ public function dropAndCreateIndex(Index $index, $table)
      *
      * @param ForeignKeyConstraint $foreignKey An associative array that defines properties of the foreign key to be created.
      * @param Table|string         $table      The name of the table on which the foreign key is to be created.
-     *
-     * @return void
      */
-    public function dropAndCreateForeignKey(ForeignKeyConstraint $foreignKey, $table)
+    public function dropAndCreateForeignKey(ForeignKeyConstraint $foreignKey, $table) : void
     {
         $this->tryMethod('dropForeignKey', $foreignKey, $table);
         $this->createForeignKey($foreignKey, $table);
@@ -531,11 +480,9 @@ public function dropAndCreateForeignKey(ForeignKeyConstraint $foreignKey, $table
     /**
      * Drops and create a new sequence.
      *
-     * @return void
-     *
      * @throws ConnectionException If something fails at database level.
      */
-    public function dropAndCreateSequence(Sequence $sequence)
+    public function dropAndCreateSequence(Sequence $sequence) : void
     {
         $this->tryMethod('dropSequence', $sequence->getQuotedName($this->_platform));
         $this->createSequence($sequence);
@@ -543,10 +490,8 @@ public function dropAndCreateSequence(Sequence $sequence)
 
     /**
      * Drops and creates a new table.
-     *
-     * @return void
      */
-    public function dropAndCreateTable(Table $table)
+    public function dropAndCreateTable(Table $table) : void
     {
         $this->tryMethod('dropTable', $table->getQuotedName($this->_platform));
         $this->createTable($table);
@@ -554,12 +499,8 @@ public function dropAndCreateTable(Table $table)
 
     /**
      * Drops and creates a new database.
-     *
-     * @param string $database The name of the database to create.
-     *
-     * @return void
      */
-    public function dropAndCreateDatabase($database)
+    public function dropAndCreateDatabase(string $database) : void
     {
         $this->tryMethod('dropDatabase', $database);
         $this->createDatabase($database);
@@ -567,10 +508,8 @@ public function dropAndCreateDatabase($database)
 
     /**
      * Drops and creates a new view.
-     *
-     * @return void
      */
-    public function dropAndCreateView(View $view)
+    public function dropAndCreateView(View $view) : void
     {
         $this->tryMethod('dropView', $view->getQuotedName($this->_platform));
         $this->createView($view);
@@ -580,10 +519,8 @@ public function dropAndCreateView(View $view)
 
     /**
      * Alters an existing tables schema.
-     *
-     * @return void
      */
-    public function alterTable(TableDiff $tableDiff)
+    public function alterTable(TableDiff $tableDiff) : void
     {
         $queries = $this->_platform->getAlterTableSQL($tableDiff);
 
@@ -598,13 +535,8 @@ public function alterTable(TableDiff $tableDiff)
 
     /**
      * Renames a given table to another name.
-     *
-     * @param string $name    The current name of the table.
-     * @param string $newName The new name of the table.
-     *
-     * @return void
      */
-    public function renameTable($name, $newName)
+    public function renameTable(string $name, string $newName) : void
     {
         $tableDiff          = new TableDiff($name);
         $tableDiff->newName = $newName;
@@ -617,11 +549,11 @@ public function renameTable($name, $newName)
      */
 
     /**
-     * @param mixed[] $databases
+     * @param array<int, mixed> $databases
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    protected function _getPortableDatabasesList($databases)
+    protected function _getPortableDatabasesList(array $databases) : array
     {
         $list = [];
         foreach ($databases as $value) {
@@ -640,11 +572,11 @@ protected function _getPortableDatabasesList($databases)
     /**
      * Converts a list of namespace names from the native DBMS data definition to a portable Doctrine definition.
      *
-     * @param mixed[][] $namespaces The list of namespace names in the native DBMS data definition.
+     * @param array<int, array<int, mixed>> $namespaces The list of namespace names in the native DBMS data definition.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    protected function getPortableNamespacesList(array $namespaces)
+    protected function getPortableNamespacesList(array $namespaces) : array
     {
         $namespacesList = [];
 
@@ -656,64 +588,29 @@ protected function getPortableNamespacesList(array $namespaces)
     }
 
     /**
-     * @param mixed $database
-     *
-     * @return mixed
+     * @param array<string, string> $database
      */
-    protected function _getPortableDatabaseDefinition($database)
+    protected function _getPortableDatabaseDefinition(array $database) : string
     {
-        return $database;
+        return array_shift($database);
     }
 
     /**
      * Converts a namespace definition from the native DBMS data definition to a portable Doctrine definition.
      *
-     * @param mixed[] $namespace The native DBMS namespace definition.
-     *
-     * @return mixed
-     */
-    protected function getPortableNamespaceDefinition(array $namespace)
-    {
-        return $namespace;
-    }
-
-    /**
-     * @param mixed[][] $functions
-     *
-     * @return mixed[][]
-     */
-    protected function _getPortableFunctionsList($functions)
-    {
-        $list = [];
-        foreach ($functions as $value) {
-            $value = $this->_getPortableFunctionDefinition($value);
-
-            if (! $value) {
-                continue;
-            }
-
-            $list[] = $value;
-        }
-
-        return $list;
-    }
-
-    /**
-     * @param mixed[] $function
-     *
-     * @return mixed
+     * @param array<string|int, mixed> $namespace The native DBMS namespace definition.
      */
-    protected function _getPortableFunctionDefinition($function)
+    protected function getPortableNamespaceDefinition(array $namespace) : string
     {
-        return $function;
+        return array_shift($namespace);
     }
 
     /**
-     * @param mixed[][] $triggers
+     * @param array<int, array<int, mixed>> $triggers
      *
-     * @return mixed[][]
+     * @return array<int, string>
      */
-    protected function _getPortableTriggersList($triggers)
+    protected function _getPortableTriggersList(array $triggers)
     {
         $list = [];
         foreach ($triggers as $value) {
@@ -730,21 +627,19 @@ protected function _getPortableTriggersList($triggers)
     }
 
     /**
-     * @param mixed[] $trigger
-     *
-     * @return mixed
+     * @param array<string|int, mixed> $trigger
      */
-    protected function _getPortableTriggerDefinition($trigger)
+    protected function _getPortableTriggerDefinition(array $trigger) : string
     {
-        return $trigger;
+        return array_shift($trigger);
     }
 
     /**
-     * @param mixed[][] $sequences
+     * @param array<int, array<string, mixed>> $sequences
      *
-     * @return Sequence[]
+     * @return array<int, Sequence>
      */
-    protected function _getPortableSequencesList($sequences)
+    protected function _getPortableSequencesList(array $sequences) : array
     {
         $list = [];
 
@@ -756,13 +651,11 @@ protected function _getPortableSequencesList($sequences)
     }
 
     /**
-     * @param mixed[] $sequence
-     *
-     * @return Sequence
+     * @param array<string, mixed> $sequence
      *
      * @throws DBALException
      */
-    protected function _getPortableSequenceDefinition($sequence)
+    protected function _getPortableSequenceDefinition(array $sequence) : Sequence
     {
         throw NotSupported::new('Sequences');
     }
@@ -772,13 +665,11 @@ protected function _getPortableSequenceDefinition($sequence)
      *
      * The name of the created column instance however is kept in its case.
      *
-     * @param string    $table        The name of the table.
-     * @param string    $database
-     * @param mixed[][] $tableColumns
+     * @param array<int, array<string, mixed>> $tableColumns
      *
-     * @return Column[]
+     * @return array<string, Column>
      */
-    protected function _getPortableTableColumnList($table, $database, $tableColumns)
+    protected function _getPortableTableColumnList(string $table, string $database, array $tableColumns) : array
     {
         $eventManager = $this->_platform->getEventManager();
 
@@ -813,18 +704,16 @@ protected function _getPortableTableColumnList($table, $database, $tableColumns)
     /**
      * Gets Table Column Definition.
      *
-     * @param mixed[] $tableColumn
-     *
-     * @return Column
+     * @param array<string, mixed> $tableColumn
      */
-    abstract protected function _getPortableTableColumnDefinition($tableColumn);
+    abstract protected function _getPortableTableColumnDefinition(array $tableColumn) : Column;
 
     /**
      * Aggregates and groups the index results according to the required data result.
      *
-     * @param mixed[][] $tableIndexRows
+     * @param array<int, array<string, mixed>> $tableIndexRows
      *
-     * @return Index[]
+     * @return array<string, Index>
      */
     protected function _getPortableTableIndexesList(array $tableIndexRows, string $tableName) : array
     {
@@ -889,11 +778,11 @@ protected function _getPortableTableIndexesList(array $tableIndexRows, string $t
     }
 
     /**
-     * @param mixed[][] $tables
+     * @param array<int, array<string, mixed>> $tables
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    protected function _getPortableTablesList($tables)
+    protected function _getPortableTablesList(array $tables) : array
     {
         $list = [];
         foreach ($tables as $value) {
@@ -910,21 +799,19 @@ protected function _getPortableTablesList($tables)
     }
 
     /**
-     * @param mixed $table
-     *
-     * @return string
+     * @param array<string, string> $table
      */
-    protected function _getPortableTableDefinition($table)
+    protected function _getPortableTableDefinition(array $table) : string
     {
-        return $table;
+        return array_shift($table);
     }
 
     /**
-     * @param mixed[][] $users
+     * @param array<int, array<string, mixed>> $users
      *
-     * @return string[][]
+     * @return array<int, array<string, mixed>>
      */
-    protected function _getPortableUsersList($users)
+    protected function _getPortableUsersList(array $users) : array
     {
         $list = [];
         foreach ($users as $value) {
@@ -941,53 +828,46 @@ protected function _getPortableUsersList($users)
     }
 
     /**
-     * @param string[] $user
+     * @param array<string, mixed> $user
      *
-     * @return string[]
+     * @return array<string, mixed>
      */
-    protected function _getPortableUserDefinition($user)
+    protected function _getPortableUserDefinition(array $user) : array
     {
         return $user;
     }
 
     /**
-     * @param mixed[][] $views
+     * @param array<int, array<string, mixed>> $views
      *
-     * @return View[]
+     * @return array<string, View>
      */
-    protected function _getPortableViewsList($views)
+    protected function _getPortableViewsList(array $views) : array
     {
         $list = [];
         foreach ($views as $value) {
-            $view = $this->_getPortableViewDefinition($value);
-
-            if (! $view) {
-                continue;
-            }
-
-            $viewName        = strtolower($view->getQuotedName($this->_platform));
-            $list[$viewName] = $view;
+            $view        = $this->_getPortableViewDefinition($value);
+            $name        = strtolower($view->getQuotedName($this->_platform));
+            $list[$name] = $view;
         }
 
         return $list;
     }
 
     /**
-     * @param mixed[] $view
-     *
-     * @return View|false
+     * @param array<string, mixed> $view
      */
-    protected function _getPortableViewDefinition($view)
+    protected function _getPortableViewDefinition(array $view) : View
     {
-        return false;
+        throw NotSupported::new('Views');
     }
 
     /**
-     * @param mixed[][] $tableForeignKeys
+     * @param array<int|string, array<string, mixed>> $tableForeignKeys
      *
-     * @return ForeignKeyConstraint[]
+     * @return array<int, ForeignKeyConstraint>
      */
-    protected function _getPortableTableForeignKeysList($tableForeignKeys)
+    protected function _getPortableTableForeignKeysList(array $tableForeignKeys) : array
     {
         $list = [];
 
@@ -999,21 +879,17 @@ protected function _getPortableTableForeignKeysList($tableForeignKeys)
     }
 
     /**
-     * @param mixed $tableForeignKey
-     *
-     * @return ForeignKeyConstraint
+     * @param array<string, mixed> $tableForeignKey
      */
-    protected function _getPortableTableForeignKeyDefinition($tableForeignKey)
+    protected function _getPortableTableForeignKeyDefinition(array $tableForeignKey) : ForeignKeyConstraint
     {
-        return $tableForeignKey;
+        throw NotSupported::new('ForeignKey');
     }
 
     /**
-     * @param string[]|string $sql
-     *
-     * @return void
+     * @param array<int, string>|string $sql
      */
-    protected function _execSql($sql)
+    protected function _execSql($sql) : void
     {
         foreach ((array) $sql as $query) {
             $this->_conn->executeUpdate($query);
@@ -1022,10 +898,8 @@ protected function _execSql($sql)
 
     /**
      * Creates a schema instance for the current database.
-     *
-     * @return Schema
      */
-    public function createSchema()
+    public function createSchema() : Schema
     {
         $namespaces = [];
 
@@ -1046,10 +920,8 @@ public function createSchema()
 
     /**
      * Creates the configuration for this schema.
-     *
-     * @return SchemaConfig
      */
-    public function createSchemaConfig()
+    public function createSchemaConfig() : SchemaConfig
     {
         $schemaConfig = new SchemaConfig();
         $schemaConfig->setMaxIdentifierLength($this->_platform->getMaxIdentifierLength());
@@ -1081,9 +953,9 @@ public function createSchemaConfig()
      * For databases that don't support subschema/namespaces this method
      * returns the name of the currently connected database.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getSchemaSearchPaths()
+    public function getSchemaSearchPaths() : array
     {
         return [$this->_conn->getDatabase()];
     }
@@ -1104,4 +976,16 @@ final protected function extractDoctrineTypeFromComment(?string &$comment) : ?st
 
         return $match[2];
     }
+
+    /**
+     * @throws DatabaseRequired
+     */
+    private function ensureDatabase(?string $database, string $methodName) : string
+    {
+        if ($database === null) {
+            throw DatabaseRequired::new($methodName);
+        }
+
+        return $database;
+    }
 }
diff --git a/lib/Doctrine/DBAL/Schema/Column.php b/lib/Doctrine/DBAL/Schema/Column.php
index fa45a953f0b..928f0485ec2 100644
--- a/lib/Doctrine/DBAL/Schema/Column.php
+++ b/lib/Doctrine/DBAL/Schema/Column.php
@@ -43,7 +43,7 @@ class Column extends AbstractAsset
     /** @var bool */
     protected $_autoincrement = false;
 
-    /** @var mixed[] */
+    /** @var array<string, mixed> */
     protected $_platformOptions = [];
 
     /** @var string|null */
@@ -52,13 +52,13 @@ class Column extends AbstractAsset
     /** @var string|null */
     protected $_comment;
 
-    /** @var mixed[] */
+    /** @var array<string, mixed> */
     protected $_customSchemaOptions = [];
 
     /**
      * Creates a new Column.
      *
-     * @param mixed[] $options
+     * @param array<string, mixed> $options
      */
     public function __construct(string $name, Type $type, array $options = [])
     {
@@ -68,7 +68,7 @@ public function __construct(string $name, Type $type, array $options = [])
     }
 
     /**
-     * @param mixed[] $options
+     * @param array<string, mixed> $options
      */
     public function setOptions(array $options) : self
     {
@@ -154,7 +154,7 @@ public function setDefault($default) : self
     }
 
     /**
-     * @param mixed[] $platformOptions
+     * @param array<string, mixed> $platformOptions
      */
     public function setPlatformOptions(array $platformOptions) : self
     {
@@ -224,7 +224,7 @@ public function getDefault()
     }
 
     /**
-     * @return mixed[]
+     * @return array<string, mixed>
      */
     public function getPlatformOptions() : array
     {
@@ -297,7 +297,7 @@ public function getCustomSchemaOption(string $name)
     }
 
     /**
-     * @param mixed[] $customSchemaOptions
+     * @param array<string, mixed> $customSchemaOptions
      */
     public function setCustomSchemaOptions(array $customSchemaOptions) : self
     {
@@ -307,7 +307,7 @@ public function setCustomSchemaOptions(array $customSchemaOptions) : self
     }
 
     /**
-     * @return mixed[]
+     * @return array<string, mixed>
      */
     public function getCustomSchemaOptions() : array
     {
@@ -315,7 +315,7 @@ public function getCustomSchemaOptions() : array
     }
 
     /**
-     * @return mixed[]
+     * @return array<string, mixed>
      */
     public function toArray() : array
     {
diff --git a/lib/Doctrine/DBAL/Schema/ColumnDiff.php b/lib/Doctrine/DBAL/Schema/ColumnDiff.php
index f98f9108bfd..14c0d78ed92 100644
--- a/lib/Doctrine/DBAL/Schema/ColumnDiff.php
+++ b/lib/Doctrine/DBAL/Schema/ColumnDiff.php
@@ -17,17 +17,16 @@ class ColumnDiff
     /** @var Column */
     public $column;
 
-    /** @var string[] */
+    /** @var array<int, string> */
     public $changedProperties = [];
 
     /** @var Column|null */
     public $fromColumn;
 
     /**
-     * @param string   $oldColumnName
-     * @param string[] $changedProperties
+     * @param array<string> $changedProperties
      */
-    public function __construct($oldColumnName, Column $column, array $changedProperties = [], ?Column $fromColumn = null)
+    public function __construct(string $oldColumnName, Column $column, array $changedProperties = [], ?Column $fromColumn = null)
     {
         $this->oldColumnName     = $oldColumnName;
         $this->column            = $column;
@@ -35,20 +34,12 @@ public function __construct($oldColumnName, Column $column, array $changedProper
         $this->fromColumn        = $fromColumn;
     }
 
-    /**
-     * @param string $propertyName
-     *
-     * @return bool
-     */
-    public function hasChanged($propertyName)
+    public function hasChanged(string $propertyName) : bool
     {
         return in_array($propertyName, $this->changedProperties);
     }
 
-    /**
-     * @return Identifier
-     */
-    public function getOldColumnName()
+    public function getOldColumnName() : Identifier
     {
         $quote = $this->fromColumn && $this->fromColumn->isQuoted();
 
diff --git a/lib/Doctrine/DBAL/Schema/Comparator.php b/lib/Doctrine/DBAL/Schema/Comparator.php
index a59e71ad1bc..5b321a46dcf 100644
--- a/lib/Doctrine/DBAL/Schema/Comparator.php
+++ b/lib/Doctrine/DBAL/Schema/Comparator.php
@@ -21,10 +21,7 @@
  */
 class Comparator
 {
-    /**
-     * @return SchemaDiff
-     */
-    public static function compareSchemas(Schema $fromSchema, Schema $toSchema)
+    public static function compareSchemas(Schema $fromSchema, Schema $toSchema) : SchemaDiff
     {
         $c = new self();
 
@@ -37,10 +34,8 @@ public static function compareSchemas(Schema $fromSchema, Schema $toSchema)
      * The returned differences are returned in such a way that they contain the
      * operations to change the schema stored in $fromSchema to the schema that is
      * stored in $toSchema.
-     *
-     * @return SchemaDiff
      */
-    public function compare(Schema $fromSchema, Schema $toSchema)
+    public function compare(Schema $fromSchema, Schema $toSchema) : SchemaDiff
     {
         $diff             = new SchemaDiff();
         $diff->fromSchema = $fromSchema;
@@ -69,7 +64,7 @@ public function compare(Schema $fromSchema, Schema $toSchema)
                 $diff->newTables[$tableName] = $toSchema->getTable($tableName);
             } else {
                 $tableDifferences = $this->diffTable($fromSchema->getTable($tableName), $toSchema->getTable($tableName));
-                if ($tableDifferences !== false) {
+                if ($tableDifferences !== null) {
                     $diff->changedTables[$tableName] = $tableDifferences;
                 }
             }
@@ -152,13 +147,7 @@ public function compare(Schema $fromSchema, Schema $toSchema)
         return $diff;
     }
 
-    /**
-     * @param Schema   $schema
-     * @param Sequence $sequence
-     *
-     * @return bool
-     */
-    private function isAutoIncrementSequenceInSchema($schema, $sequence)
+    private function isAutoIncrementSequenceInSchema(Schema $schema, Sequence $sequence) : bool
     {
         foreach ($schema->getTables() as $table) {
             if ($sequence->isAutoIncrementsFor($table)) {
@@ -169,10 +158,7 @@ private function isAutoIncrementSequenceInSchema($schema, $sequence)
         return false;
     }
 
-    /**
-     * @return bool
-     */
-    public function diffSequence(Sequence $sequence1, Sequence $sequence2)
+    public function diffSequence(Sequence $sequence1, Sequence $sequence2) : bool
     {
         if ($sequence1->getAllocationSize() !== $sequence2->getAllocationSize()) {
             return true;
@@ -185,10 +171,8 @@ public function diffSequence(Sequence $sequence1, Sequence $sequence2)
      * Returns the difference between the tables $table1 and $table2.
      *
      * If there are no differences this method returns the boolean false.
-     *
-     * @return TableDiff|false
      */
-    public function diffTable(Table $table1, Table $table2)
+    public function diffTable(Table $table1, Table $table2) : ?TableDiff
     {
         $changes                     = 0;
         $tableDifferences            = new TableDiff($table1->getName());
@@ -294,16 +278,14 @@ public function diffTable(Table $table1, Table $table2)
             $changes++;
         }
 
-        return $changes ? $tableDifferences : false;
+        return $changes ? $tableDifferences : null;
     }
 
     /**
      * Try to find columns that only changed their name, rename operations maybe cheaper than add/drop
      * however ambiguities between different possibilities should not lead to renaming at all.
-     *
-     * @return void
      */
-    private function detectColumnRenamings(TableDiff $tableDifferences)
+    private function detectColumnRenamings(TableDiff $tableDifferences) : void
     {
         $renameCandidates = [];
         foreach ($tableDifferences->addedColumns as $addedColumnName => $addedColumn) {
@@ -340,10 +322,8 @@ private function detectColumnRenamings(TableDiff $tableDifferences)
     /**
      * Try to find indexes that only changed their name, rename operations maybe cheaper than add/drop
      * however ambiguities between different possibilities should not lead to renaming at all.
-     *
-     * @return void
      */
-    private function detectIndexRenamings(TableDiff $tableDifferences)
+    private function detectIndexRenamings(TableDiff $tableDifferences) : void
     {
         $renameCandidates = [];
 
@@ -384,10 +364,7 @@ private function detectIndexRenamings(TableDiff $tableDifferences)
         }
     }
 
-    /**
-     * @return bool
-     */
-    public function diffForeignKey(ForeignKeyConstraint $key1, ForeignKeyConstraint $key2)
+    public function diffForeignKey(ForeignKeyConstraint $key1, ForeignKeyConstraint $key2) : bool
     {
         if (array_map('strtolower', $key1->getUnquotedLocalColumns()) !== array_map('strtolower', $key2->getUnquotedLocalColumns())) {
             return true;
@@ -414,9 +391,9 @@ public function diffForeignKey(ForeignKeyConstraint $key1, ForeignKeyConstraint
      * If there are differences this method returns $field2, otherwise the
      * boolean false.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function diffColumn(Column $column1, Column $column2)
+    public function diffColumn(Column $column1, Column $column2) : array
     {
         $properties1 = $column1->toArray();
         $properties2 = $column2->toArray();
@@ -502,10 +479,8 @@ public function diffColumn(Column $column1, Column $column2)
      *
      * Compares $index1 with $index2 and returns $index2 if there are any
      * differences or false in case there are no differences.
-     *
-     * @return bool
      */
-    public function diffIndex(Index $index1, Index $index2)
+    public function diffIndex(Index $index1, Index $index2) : bool
     {
         return ! ($index1->isFullfilledBy($index2) && $index2->isFullfilledBy($index1));
     }
diff --git a/lib/Doctrine/DBAL/Schema/Constraint.php b/lib/Doctrine/DBAL/Schema/Constraint.php
index c939a06e33e..2c167b9de67 100644
--- a/lib/Doctrine/DBAL/Schema/Constraint.php
+++ b/lib/Doctrine/DBAL/Schema/Constraint.php
@@ -11,23 +11,17 @@
  */
 interface Constraint
 {
-    /**
-     * @return string
-     */
-    public function getName();
+    public function getName() : string;
 
-    /**
-     * @return string
-     */
-    public function getQuotedName(AbstractPlatform $platform);
+    public function getQuotedName(AbstractPlatform $platform) : string;
 
     /**
      * Returns the names of the referencing table columns
      * the constraint is associated with.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getColumns();
+    public function getColumns() : array;
 
     /**
      * Returns the quoted representation of the column names
@@ -39,7 +33,7 @@ public function getColumns();
      *
      * @param AbstractPlatform $platform The platform to use for quotation.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getQuotedColumns(AbstractPlatform $platform);
+    public function getQuotedColumns(AbstractPlatform $platform) : array;
 }
diff --git a/lib/Doctrine/DBAL/Schema/DB2SchemaManager.php b/lib/Doctrine/DBAL/Schema/DB2SchemaManager.php
index 7a449fe16e9..7bec112e9b3 100644
--- a/lib/Doctrine/DBAL/Schema/DB2SchemaManager.php
+++ b/lib/Doctrine/DBAL/Schema/DB2SchemaManager.php
@@ -43,7 +43,7 @@ public function listTableNames() : array
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableColumnDefinition($tableColumn)
+    protected function _getPortableTableColumnDefinition(array $tableColumn) : Column
     {
         $tableColumn = array_change_key_case($tableColumn, CASE_LOWER);
 
@@ -105,7 +105,7 @@ protected function _getPortableTableColumnDefinition($tableColumn)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTablesList($tables)
+    protected function _getPortableTablesList(array $tables) : array
     {
         $tableNames = [];
         foreach ($tables as $tableRow) {
@@ -132,7 +132,7 @@ protected function _getPortableTableIndexesList(array $tableIndexRows, string $t
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableForeignKeyDefinition($tableForeignKey)
+    protected function _getPortableTableForeignKeyDefinition(array $tableForeignKey) : ForeignKeyConstraint
     {
         return new ForeignKeyConstraint(
             $tableForeignKey['local_columns'],
@@ -146,7 +146,7 @@ protected function _getPortableTableForeignKeyDefinition($tableForeignKey)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableForeignKeysList($tableForeignKeys)
+    protected function _getPortableTableForeignKeysList(array $tableForeignKeys) : array
     {
         $foreignKeys = [];
 
@@ -176,7 +176,7 @@ protected function _getPortableTableForeignKeysList($tableForeignKeys)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableViewDefinition($view)
+    protected function _getPortableViewDefinition(array $view) : View
     {
         $view = array_change_key_case($view, CASE_LOWER);
         // sadly this still segfaults on PDO_IBM, see http://pecl.php.net/bugs/bug.php?id=17199
@@ -191,7 +191,7 @@ protected function _getPortableViewDefinition($view)
         return new View($view['name'], $sql);
     }
 
-    public function listTableDetails($tableName) : Table
+    public function listTableDetails(string $tableName) : Table
     {
         $table = parent::listTableDetails($tableName);
 
diff --git a/lib/Doctrine/DBAL/Schema/ForeignKeyConstraint.php b/lib/Doctrine/DBAL/Schema/ForeignKeyConstraint.php
index 3ccd2ede590..6b7844f4b42 100644
--- a/lib/Doctrine/DBAL/Schema/ForeignKeyConstraint.php
+++ b/lib/Doctrine/DBAL/Schema/ForeignKeyConstraint.php
@@ -27,9 +27,8 @@ class ForeignKeyConstraint extends AbstractAsset implements Constraint
 
     /**
      * Asset identifier instances of the referencing table column names the foreign key constraint is associated with.
-     * array($columnName => Identifier)
      *
-     * @var Identifier[]
+     * @var array<string, Identifier>
      */
     protected $_localColumnNames;
 
@@ -42,27 +41,26 @@ class ForeignKeyConstraint extends AbstractAsset implements Constraint
 
     /**
      * Asset identifier instances of the referenced table column names the foreign key constraint is associated with.
-     * array($columnName => Identifier)
      *
-     * @var Identifier[]
+     * @var array<string, Identifier>
      */
     protected $_foreignColumnNames;
 
     /**
      * Options associated with the foreign key constraint.
      *
-     * @var mixed[]
+     * @var array<string, mixed>
      */
     protected $_options;
 
     /**
      * Initializes the foreign key constraint.
      *
-     * @param string[]     $localColumnNames   Names of the referencing table columns.
-     * @param Table|string $foreignTableName   Referenced table.
-     * @param string[]     $foreignColumnNames Names of the referenced table columns.
-     * @param string|null  $name               Name of the foreign key constraint.
-     * @param mixed[]      $options            Options associated with the foreign key constraint.
+     * @param array<int, string>   $localColumnNames   Names of the referencing table columns.
+     * @param Table|string         $foreignTableName   Referenced table.
+     * @param array<int, string>   $foreignColumnNames Names of the referenced table columns.
+     * @param string|null          $name               Name of the foreign key constraint.
+     * @param array<string, mixed> $options            Options associated with the foreign key constraint.
      */
     public function __construct(array $localColumnNames, $foreignTableName, array $foreignColumnNames, $name = null, array $options = [])
     {
@@ -83,9 +81,9 @@ public function __construct(array $localColumnNames, $foreignTableName, array $f
     }
 
     /**
-     * @param string[] $names
+     * @param array<int, string> $names
      *
-     * @return Identifier[]
+     * @return array<string, Identifier>
      */
     private function createIdentifierMap(array $names) : array
     {
@@ -101,10 +99,8 @@ private function createIdentifierMap(array $names) : array
     /**
      * Returns the name of the referencing table
      * the foreign key constraint is associated with.
-     *
-     * @return string
      */
-    public function getLocalTableName()
+    public function getLocalTableName() : string
     {
         return $this->_localTable->getName();
     }
@@ -112,20 +108,13 @@ public function getLocalTableName()
     /**
      * Sets the Table instance of the referencing table
      * the foreign key constraint is associated with.
-     *
-     * @param Table $table Instance of the referencing table.
-     *
-     * @return void
      */
-    public function setLocalTable(Table $table)
+    public function setLocalTable(Table $table) : void
     {
         $this->_localTable = $table;
     }
 
-    /**
-     * @return Table
-     */
-    public function getLocalTable()
+    public function getLocalTable() : Table
     {
         return $this->_localTable;
     }
@@ -134,9 +123,9 @@ public function getLocalTable()
      * Returns the names of the referencing table columns
      * the foreign key constraint is associated with.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getLocalColumns()
+    public function getLocalColumns() : array
     {
         return array_keys($this->_localColumnNames);
     }
@@ -151,9 +140,9 @@ public function getLocalColumns()
      *
      * @param AbstractPlatform $platform The platform to use for quotation.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getQuotedLocalColumns(AbstractPlatform $platform)
+    public function getQuotedLocalColumns(AbstractPlatform $platform) : array
     {
         $columns = [];
 
@@ -167,9 +156,9 @@ public function getQuotedLocalColumns(AbstractPlatform $platform)
     /**
      * Returns unquoted representation of local table column names for comparison with other FK
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getUnquotedLocalColumns()
+    public function getUnquotedLocalColumns() : array
     {
         return array_map([$this, 'trimQuotes'], $this->getLocalColumns());
     }
@@ -177,9 +166,9 @@ public function getUnquotedLocalColumns()
     /**
      * Returns unquoted representation of foreign table column names for comparison with other FK
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getUnquotedForeignColumns()
+    public function getUnquotedForeignColumns() : array
     {
         return array_map([$this, 'trimQuotes'], $this->getForeignColumns());
     }
@@ -189,7 +178,7 @@ public function getUnquotedForeignColumns()
      *
      * @see getLocalColumns
      */
-    public function getColumns()
+    public function getColumns() : array
     {
         return $this->getLocalColumns();
     }
@@ -206,9 +195,9 @@ public function getColumns()
      *
      * @param AbstractPlatform $platform The platform to use for quotation.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getQuotedColumns(AbstractPlatform $platform)
+    public function getQuotedColumns(AbstractPlatform $platform) : array
     {
         return $this->getQuotedLocalColumns($platform);
     }
@@ -216,20 +205,16 @@ public function getQuotedColumns(AbstractPlatform $platform)
     /**
      * Returns the name of the referenced table
      * the foreign key constraint is associated with.
-     *
-     * @return string
      */
-    public function getForeignTableName()
+    public function getForeignTableName() : string
     {
         return $this->_foreignTableName->getName();
     }
 
     /**
      * Returns the non-schema qualified foreign table name.
-     *
-     * @return string
      */
-    public function getUnqualifiedForeignTableName()
+    public function getUnqualifiedForeignTableName() : string
     {
         $name     = $this->_foreignTableName->getName();
         $position = strrpos($name, '.');
@@ -250,10 +235,8 @@ public function getUnqualifiedForeignTableName()
      * Otherwise the plain unquoted value as inserted is returned.
      *
      * @param AbstractPlatform $platform The platform to use for quotation.
-     *
-     * @return string
      */
-    public function getQuotedForeignTableName(AbstractPlatform $platform)
+    public function getQuotedForeignTableName(AbstractPlatform $platform) : string
     {
         return $this->_foreignTableName->getQuotedName($platform);
     }
@@ -262,9 +245,9 @@ public function getQuotedForeignTableName(AbstractPlatform $platform)
      * Returns the names of the referenced table columns
      * the foreign key constraint is associated with.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getForeignColumns()
+    public function getForeignColumns() : array
     {
         return array_keys($this->_foreignColumnNames);
     }
@@ -279,9 +262,9 @@ public function getForeignColumns()
      *
      * @param AbstractPlatform $platform The platform to use for quotation.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getQuotedForeignColumns(AbstractPlatform $platform)
+    public function getQuotedForeignColumns(AbstractPlatform $platform) : array
     {
         $columns = [];
 
@@ -295,12 +278,8 @@ public function getQuotedForeignColumns(AbstractPlatform $platform)
     /**
      * Returns whether or not a given option
      * is associated with the foreign key constraint.
-     *
-     * @param string $name Name of the option to check.
-     *
-     * @return bool
      */
-    public function hasOption($name)
+    public function hasOption(string $name) : bool
     {
         return isset($this->_options[$name]);
     }
@@ -308,11 +287,9 @@ public function hasOption($name)
     /**
      * Returns an option associated with the foreign key constraint.
      *
-     * @param string $name Name of the option the foreign key constraint is associated with.
-     *
      * @return mixed
      */
-    public function getOption($name)
+    public function getOption(string $name)
     {
         return $this->_options[$name];
     }
@@ -320,9 +297,9 @@ public function getOption($name)
     /**
      * Returns the options associated with the foreign key constraint.
      *
-     * @return mixed[]
+     * @return array<string, mixed>
      */
-    public function getOptions()
+    public function getOptions() : array
     {
         return $this->_options;
     }
@@ -330,10 +307,8 @@ public function getOptions()
     /**
      * Returns the referential action for UPDATE operations
      * on the referenced table the foreign key constraint is associated with.
-     *
-     * @return string|null
      */
-    public function onUpdate()
+    public function onUpdate() : ?string
     {
         return $this->onEvent('onUpdate');
     }
@@ -341,10 +316,8 @@ public function onUpdate()
     /**
      * Returns the referential action for DELETE operations
      * on the referenced table the foreign key constraint is associated with.
-     *
-     * @return string|null
      */
-    public function onDelete()
+    public function onDelete() : ?string
     {
         return $this->onEvent('onDelete');
     }
@@ -354,10 +327,8 @@ public function onDelete()
      * on the referenced table the foreign key constraint is associated with.
      *
      * @param string $event Name of the database operation/event to return the referential action for.
-     *
-     * @return string|null
      */
-    private function onEvent($event)
+    private function onEvent(string $event) : ?string
     {
         if (isset($this->_options[$event])) {
             $onEvent = strtoupper($this->_options[$event]);
@@ -367,7 +338,7 @@ private function onEvent($event)
             }
         }
 
-        return false;
+        return null;
     }
 
     /**
@@ -377,10 +348,8 @@ private function onEvent($event)
      * matches one of the given index's columns, `false` otherwise.
      *
      * @param Index $index The index to be checked against.
-     *
-     * @return bool
      */
-    public function intersectsIndexColumns(Index $index)
+    public function intersectsIndexColumns(Index $index) : bool
     {
         foreach ($index->getColumns() as $indexColumn) {
             foreach ($this->_localColumnNames as $localColumn) {
diff --git a/lib/Doctrine/DBAL/Schema/Identifier.php b/lib/Doctrine/DBAL/Schema/Identifier.php
index 276b7824f1a..c3c84a7b62e 100644
--- a/lib/Doctrine/DBAL/Schema/Identifier.php
+++ b/lib/Doctrine/DBAL/Schema/Identifier.php
@@ -16,7 +16,7 @@ class Identifier extends AbstractAsset
      * @param string $identifier Identifier name to wrap.
      * @param bool   $quote      Whether to force quoting the given identifier.
      */
-    public function __construct($identifier, $quote = false)
+    public function __construct(string $identifier, bool $quote = false)
     {
         $this->_setName($identifier);
 
diff --git a/lib/Doctrine/DBAL/Schema/Index.php b/lib/Doctrine/DBAL/Schema/Index.php
index b895f3e14a8..b450c070315 100644
--- a/lib/Doctrine/DBAL/Schema/Index.php
+++ b/lib/Doctrine/DBAL/Schema/Index.php
@@ -5,23 +5,20 @@
 namespace Doctrine\DBAL\Schema;
 
 use Doctrine\DBAL\Platforms\AbstractPlatform;
-use InvalidArgumentException;
 use function array_filter;
 use function array_keys;
 use function array_map;
 use function array_search;
 use function array_shift;
 use function count;
-use function is_string;
 use function strtolower;
 
 class Index extends AbstractAsset implements Constraint
 {
     /**
      * Asset identifier instances of the column names the index is associated with.
-     * array($columnName => Identifier)
      *
-     * @var Identifier[]
+     * @var array<string, Identifier>
      */
     protected $_columns = [];
 
@@ -33,9 +30,8 @@ class Index extends AbstractAsset implements Constraint
 
     /**
      * Platform specific flags for indexes.
-     * array($flagName => true)
      *
-     * @var true[]
+     * @var array<string, true>
      */
     protected $_flags = [];
 
@@ -43,19 +39,16 @@ class Index extends AbstractAsset implements Constraint
      * Platform specific options
      *
      * @todo $_flags should eventually be refactored into options
-     * @var mixed[]
+     * @var array<string, mixed>
      */
     private $options = [];
 
     /**
-     * @param string   $indexName
-     * @param string[] $columns
-     * @param bool     $isUnique
-     * @param bool     $isPrimary
-     * @param string[] $flags
-     * @param mixed[]  $options
+     * @param array<int, string>   $columns
+     * @param array<int, string>   $flags
+     * @param array<string, mixed> $options
      */
-    public function __construct($indexName, array $columns, $isUnique = false, $isPrimary = false, array $flags = [], array $options = [])
+    public function __construct(?string $indexName, array $columns, bool $isUnique = false, bool $isPrimary = false, array $flags = [], array $options = [])
     {
         $isUnique = $isUnique || $isPrimary;
 
@@ -76,26 +69,15 @@ public function __construct($indexName, array $columns, $isUnique = false, $isPr
         }
     }
 
-    /**
-     * @param string $column
-     *
-     * @return void
-     *
-     * @throws InvalidArgumentException
-     */
-    protected function _addColumn($column)
+    protected function _addColumn(string $column) : void
     {
-        if (! is_string($column)) {
-            throw new InvalidArgumentException('Expecting a string as Index Column');
-        }
-
         $this->_columns[$column] = new Identifier($column);
     }
 
     /**
      * {@inheritdoc}
      */
-    public function getColumns()
+    public function getColumns() : array
     {
         return array_keys($this->_columns);
     }
@@ -103,7 +85,7 @@ public function getColumns()
     /**
      * {@inheritdoc}
      */
-    public function getQuotedColumns(AbstractPlatform $platform)
+    public function getQuotedColumns(AbstractPlatform $platform) : array
     {
         $subParts = $platform->supportsColumnLengthIndexes() && $this->hasOption('lengths')
             ? $this->getOption('lengths') : [];
@@ -126,46 +108,32 @@ public function getQuotedColumns(AbstractPlatform $platform)
     }
 
     /**
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getUnquotedColumns()
+    public function getUnquotedColumns() : array
     {
         return array_map([$this, 'trimQuotes'], $this->getColumns());
     }
 
     /**
      * Is the index neither unique nor primary key?
-     *
-     * @return bool
      */
-    public function isSimpleIndex()
+    public function isSimpleIndex() : bool
     {
         return ! $this->_isPrimary && ! $this->_isUnique;
     }
 
-    /**
-     * @return bool
-     */
-    public function isUnique()
+    public function isUnique() : bool
     {
         return $this->_isUnique;
     }
 
-    /**
-     * @return bool
-     */
-    public function isPrimary()
+    public function isPrimary() : bool
     {
         return $this->_isPrimary;
     }
 
-    /**
-     * @param string $columnName
-     * @param int    $pos
-     *
-     * @return bool
-     */
-    public function hasColumnAtPosition($columnName, $pos = 0)
+    public function hasColumnAtPosition(string $columnName, int $pos = 0) : bool
     {
         $columnName   = $this->trimQuotes(strtolower($columnName));
         $indexColumns = array_map('strtolower', $this->getUnquotedColumns());
@@ -176,11 +144,9 @@ public function hasColumnAtPosition($columnName, $pos = 0)
     /**
      * Checks if this index exactly spans the given column names in the correct order.
      *
-     * @param string[] $columnNames
-     *
-     * @return bool
+     * @param array<int, string> $columnNames
      */
-    public function spansColumns(array $columnNames)
+    public function spansColumns(array $columnNames) : bool
     {
         $columns         = $this->getColumns();
         $numberOfColumns = count($columns);
@@ -199,10 +165,8 @@ public function spansColumns(array $columnNames)
 
     /**
      * Checks if the other index already fulfills all the indexing and constraint needs of the current one.
-     *
-     * @return bool
      */
-    public function isFullfilledBy(Index $other)
+    public function isFullfilledBy(Index $other) : bool
     {
         // allow the other index to be equally large only. It being larger is an option
         // but it creates a problem with scenarios of the kind PRIMARY KEY(foo,bar) UNIQUE(foo)
@@ -242,10 +206,8 @@ public function isFullfilledBy(Index $other)
 
     /**
      * Detects if the other index is a non-unique, non primary index that can be overwritten by this one.
-     *
-     * @return bool
      */
-    public function overrules(Index $other)
+    public function overrules(Index $other) : bool
     {
         if ($other->isPrimary()) {
             return false;
@@ -261,9 +223,9 @@ public function overrules(Index $other)
     /**
      * Returns platform specific flags for indexes.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getFlags()
+    public function getFlags() : array
     {
         return array_keys($this->_flags);
     }
@@ -271,13 +233,9 @@ public function getFlags()
     /**
      * Adds Flag for an index that translates to platform specific handling.
      *
-     * @param string $flag
-     *
-     * @return Index
-     *
      * @example $index->addFlag('CLUSTERED')
      */
-    public function addFlag($flag)
+    public function addFlag(string $flag) : self
     {
         $this->_flags[strtolower($flag)] = true;
 
@@ -286,62 +244,45 @@ public function addFlag($flag)
 
     /**
      * Does this index have a specific flag?
-     *
-     * @param string $flag
-     *
-     * @return bool
      */
-    public function hasFlag($flag)
+    public function hasFlag(string $flag) : bool
     {
         return isset($this->_flags[strtolower($flag)]);
     }
 
     /**
      * Removes a flag.
-     *
-     * @param string $flag
-     *
-     * @return void
      */
-    public function removeFlag($flag)
+    public function removeFlag(string $flag) : void
     {
         unset($this->_flags[strtolower($flag)]);
     }
 
-    /**
-     * @param string $name
-     *
-     * @return bool
-     */
-    public function hasOption($name)
+    public function hasOption(string $name) : bool
     {
         return isset($this->options[strtolower($name)]);
     }
 
     /**
-     * @param string $name
-     *
      * @return mixed
      */
-    public function getOption($name)
+    public function getOption(string $name)
     {
         return $this->options[strtolower($name)];
     }
 
     /**
-     * @return mixed[]
+     * @return array<string, mixed>
      */
-    public function getOptions()
+    public function getOptions() : array
     {
         return $this->options;
     }
 
     /**
      * Return whether the two indexes have the same partial index
-     *
-     * @return bool
      */
-    private function samePartialIndex(Index $other)
+    private function samePartialIndex(Index $other) : bool
     {
         if ($this->hasOption('where') && $other->hasOption('where') && $this->getOption('where') === $other->getOption('where')) {
             return true;
diff --git a/lib/Doctrine/DBAL/Schema/MySqlSchemaManager.php b/lib/Doctrine/DBAL/Schema/MySqlSchemaManager.php
index 3e5a18737b9..3e358e76e78 100644
--- a/lib/Doctrine/DBAL/Schema/MySqlSchemaManager.php
+++ b/lib/Doctrine/DBAL/Schema/MySqlSchemaManager.php
@@ -48,7 +48,7 @@ class MySqlSchemaManager extends AbstractSchemaManager
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableViewDefinition($view)
+    protected function _getPortableViewDefinition(array $view) : View
     {
         return new View($view['TABLE_NAME'], $view['VIEW_DEFINITION']);
     }
@@ -56,7 +56,7 @@ protected function _getPortableViewDefinition($view)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableDefinition($table)
+    protected function _getPortableTableDefinition(array $table) : string
     {
         return array_shift($table);
     }
@@ -64,7 +64,7 @@ protected function _getPortableTableDefinition($table)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableUserDefinition($user)
+    protected function _getPortableUserDefinition(array $user) : array
     {
         return [
             'user' => $user['User'],
@@ -100,7 +100,7 @@ protected function _getPortableTableIndexesList(array $tableIndexRows, string $t
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableDatabaseDefinition($database)
+    protected function _getPortableDatabaseDefinition(array $database) : string
     {
         return $database['Database'];
     }
@@ -108,7 +108,7 @@ protected function _getPortableDatabaseDefinition($database)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableColumnDefinition($tableColumn)
+    protected function _getPortableTableColumnDefinition(array $tableColumn) : Column
     {
         $tableColumn = array_change_key_case($tableColumn, CASE_LOWER);
 
@@ -248,7 +248,7 @@ private function getMariaDb1027ColumnDefault(MariaDb1027Platform $platform, ?str
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableForeignKeysList($tableForeignKeys)
+    protected function _getPortableTableForeignKeysList(array $tableForeignKeys) : array
     {
         $list = [];
         foreach ($tableForeignKeys as $value) {
@@ -291,7 +291,10 @@ protected function _getPortableTableForeignKeysList($tableForeignKeys)
         return $result;
     }
 
-    public function listTableDetails($tableName)
+    /**
+     * {@inheritdoc}
+     */
+    public function listTableDetails(string $tableName) : Table
     {
         $table = parent::listTableDetails($tableName);
 
@@ -322,7 +325,7 @@ public function listTableDetails($tableName)
     }
 
     /**
-     * @return string[]|true[]
+     * @return array<string, string>|array<string, true>
      */
     private function parseCreateOptions(?string $string) : array
     {
diff --git a/lib/Doctrine/DBAL/Schema/OracleSchemaManager.php b/lib/Doctrine/DBAL/Schema/OracleSchemaManager.php
index df3b3fda1df..2d3def7207f 100644
--- a/lib/Doctrine/DBAL/Schema/OracleSchemaManager.php
+++ b/lib/Doctrine/DBAL/Schema/OracleSchemaManager.php
@@ -29,7 +29,7 @@ class OracleSchemaManager extends AbstractSchemaManager
     /**
      * {@inheritdoc}
      */
-    public function dropDatabase($database)
+    public function dropDatabase(string $database) : void
     {
         try {
             parent::dropDatabase($database);
@@ -58,7 +58,7 @@ public function dropDatabase($database)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableViewDefinition($view)
+    protected function _getPortableViewDefinition(array $view) : View
     {
         $view = array_change_key_case($view, CASE_LOWER);
 
@@ -68,7 +68,7 @@ protected function _getPortableViewDefinition($view)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableUserDefinition($user)
+    protected function _getPortableUserDefinition(array $user) : array
     {
         $user = array_change_key_case($user, CASE_LOWER);
 
@@ -80,7 +80,7 @@ protected function _getPortableUserDefinition($user)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableDefinition($table)
+    protected function _getPortableTableDefinition(array $table) : string
     {
         $table = array_change_key_case($table, CASE_LOWER);
 
@@ -120,7 +120,7 @@ protected function _getPortableTableIndexesList(array $tableIndexRows, string $t
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableColumnDefinition($tableColumn)
+    protected function _getPortableTableColumnDefinition(array $tableColumn) : Column
     {
         $tableColumn = array_change_key_case($tableColumn, CASE_LOWER);
 
@@ -211,7 +211,7 @@ protected function _getPortableTableColumnDefinition($tableColumn)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableForeignKeysList($tableForeignKeys)
+    protected function _getPortableTableForeignKeysList(array $tableForeignKeys) : array
     {
         $list = [];
         foreach ($tableForeignKeys as $value) {
@@ -254,7 +254,7 @@ protected function _getPortableTableForeignKeysList($tableForeignKeys)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableSequenceDefinition($sequence)
+    protected function _getPortableSequenceDefinition(array $sequence) : Sequence
     {
         $sequence = array_change_key_case($sequence, CASE_LOWER);
 
@@ -268,17 +268,7 @@ protected function _getPortableSequenceDefinition($sequence)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableFunctionDefinition($function)
-    {
-        $function = array_change_key_case($function, CASE_LOWER);
-
-        return $function['name'];
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    protected function _getPortableDatabaseDefinition($database)
+    protected function _getPortableDatabaseDefinition(array $database) : string
     {
         $database = array_change_key_case($database, CASE_LOWER);
 
@@ -288,12 +278,8 @@ protected function _getPortableDatabaseDefinition($database)
     /**
      * {@inheritdoc}
      */
-    public function createDatabase($database = null)
+    public function createDatabase(string $database) : void
     {
-        if ($database === null) {
-            $database = $this->_conn->getDatabase();
-        }
-
         $params   = $this->_conn->getParams();
         $username = $database;
         $password = $params['password'];
@@ -305,12 +291,7 @@ public function createDatabase($database = null)
         $this->_conn->executeUpdate($query);
     }
 
-    /**
-     * @param string $table
-     *
-     * @return bool
-     */
-    public function dropAutoincrement($table)
+    public function dropAutoincrement(string $table) : bool
     {
         assert($this->_platform instanceof OraclePlatform);
 
@@ -325,7 +306,7 @@ public function dropAutoincrement($table)
     /**
      * {@inheritdoc}
      */
-    public function dropTable($name)
+    public function dropTable(string $name) : void
     {
         $this->tryMethod('dropAutoincrement', $name);
 
@@ -337,12 +318,8 @@ public function dropTable($name)
      *
      * Quotes non-uppercase identifiers explicitly to preserve case
      * and thus make references to the particular identifier work.
-     *
-     * @param string $identifier The identifier to quote.
-     *
-     * @return string The quoted identifier.
      */
-    private function getQuotedIdentifierName($identifier)
+    private function getQuotedIdentifierName(string $identifier) : string
     {
         if (preg_match('/[a-z]/', $identifier)) {
             return $this->_platform->quoteIdentifier($identifier);
@@ -357,10 +334,8 @@ private function getQuotedIdentifierName($identifier)
      * This is useful to force DROP USER operations which could fail because of active user sessions.
      *
      * @param string $user The name of the user to kill sessions for.
-     *
-     * @return void
      */
-    private function killUserSessions($user)
+    private function killUserSessions(string $user) : void
     {
         $sql = <<<SQL
 SELECT
@@ -389,7 +364,7 @@ private function killUserSessions($user)
         }
     }
 
-    public function listTableDetails($tableName) : Table
+    public function listTableDetails(string $tableName) : Table
     {
         $table = parent::listTableDetails($tableName);
 
diff --git a/lib/Doctrine/DBAL/Schema/PostgreSqlSchemaManager.php b/lib/Doctrine/DBAL/Schema/PostgreSqlSchemaManager.php
index eefe838e214..b3923713ae9 100644
--- a/lib/Doctrine/DBAL/Schema/PostgreSqlSchemaManager.php
+++ b/lib/Doctrine/DBAL/Schema/PostgreSqlSchemaManager.php
@@ -32,15 +32,15 @@
  */
 class PostgreSqlSchemaManager extends AbstractSchemaManager
 {
-    /** @var string[] */
+    /** @var array<int, string> */
     private $existingSchemaPaths;
 
     /**
      * Gets all the existing schema names.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getSchemaNames()
+    public function getSchemaNames() : array
     {
         $statement = $this->_conn->executeQuery("SELECT nspname FROM pg_namespace WHERE nspname !~ '^pg_.*' AND nspname != 'information_schema'");
 
@@ -52,9 +52,9 @@ public function getSchemaNames()
      *
      * This is a PostgreSQL only function.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getSchemaSearchPaths()
+    public function getSchemaSearchPaths() : array
     {
         $params = $this->_conn->getParams();
         $schema = explode(',', $this->_conn->fetchColumn('SHOW search_path'));
@@ -71,9 +71,9 @@ public function getSchemaSearchPaths()
      *
      * This is a PostgreSQL only function.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getExistingSchemaSearchPaths()
+    public function getExistingSchemaSearchPaths() : array
     {
         if ($this->existingSchemaPaths === null) {
             $this->determineExistingSchemaSearchPaths();
@@ -86,10 +86,8 @@ public function getExistingSchemaSearchPaths()
      * Sets or resets the order of the existing schemas in the current search path of the user.
      *
      * This is a PostgreSQL only function.
-     *
-     * @return void
      */
-    public function determineExistingSchemaSearchPaths()
+    public function determineExistingSchemaSearchPaths() : void
     {
         $names = $this->getSchemaNames();
         $paths = $this->getSchemaSearchPaths();
@@ -102,7 +100,7 @@ public function determineExistingSchemaSearchPaths()
     /**
      * {@inheritdoc}
      */
-    public function dropDatabase($database)
+    public function dropDatabase(string $database) : void
     {
         try {
             parent::dropDatabase($database);
@@ -131,7 +129,7 @@ public function dropDatabase($database)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableForeignKeyDefinition($tableForeignKey)
+    protected function _getPortableTableForeignKeyDefinition(array $tableForeignKey) : ForeignKeyConstraint
     {
         $onUpdate       = null;
         $onDelete       = null;
@@ -166,7 +164,7 @@ protected function _getPortableTableForeignKeyDefinition($tableForeignKey)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTriggerDefinition($trigger)
+    protected function _getPortableTriggerDefinition(array $trigger) : string
     {
         return $trigger['trigger_name'];
     }
@@ -174,7 +172,7 @@ protected function _getPortableTriggerDefinition($trigger)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableViewDefinition($view)
+    protected function _getPortableViewDefinition(array $view) : View
     {
         return new View($view['schemaname'] . '.' . $view['viewname'], $view['definition']);
     }
@@ -182,7 +180,7 @@ protected function _getPortableViewDefinition($view)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableUserDefinition($user)
+    protected function _getPortableUserDefinition(array $user) : array
     {
         return [
             'user' => $user['usename'],
@@ -193,7 +191,7 @@ protected function _getPortableUserDefinition($user)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableDefinition($table)
+    protected function _getPortableTableDefinition(array $table) : string
     {
         $schemas     = $this->getExistingSchemaSearchPaths();
         $firstSchema = array_shift($schemas);
@@ -248,7 +246,7 @@ protected function _getPortableTableIndexesList(array $tableIndexRows, string $t
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableDatabaseDefinition($database)
+    protected function _getPortableDatabaseDefinition(array $database) : string
     {
         return $database['datname'];
     }
@@ -256,7 +254,7 @@ protected function _getPortableDatabaseDefinition($database)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableSequencesList($sequences)
+    protected function _getPortableSequencesList(array $sequences) : array
     {
         $sequenceDefinitions = [];
 
@@ -282,7 +280,7 @@ protected function _getPortableSequencesList($sequences)
     /**
      * {@inheritdoc}
      */
-    protected function getPortableNamespaceDefinition(array $namespace)
+    protected function getPortableNamespaceDefinition(array $namespace) : string
     {
         return $namespace['nspname'];
     }
@@ -290,7 +288,7 @@ protected function getPortableNamespaceDefinition(array $namespace)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableSequenceDefinition($sequence)
+    protected function _getPortableSequenceDefinition(array $sequence) : Sequence
     {
         if ($sequence['schemaname'] !== 'public') {
             $sequenceName = $sequence['schemaname'] . '.' . $sequence['relname'];
@@ -311,7 +309,7 @@ protected function _getPortableSequenceDefinition($sequence)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableColumnDefinition($tableColumn)
+    protected function _getPortableTableColumnDefinition(array $tableColumn) : Column
     {
         $tableColumn = array_change_key_case($tableColumn, CASE_LOWER);
 
@@ -493,7 +491,7 @@ private function parseDefaultExpression(?string $default) : ?string
         return str_replace("''", "'", $default);
     }
 
-    public function listTableDetails($tableName) : Table
+    public function listTableDetails(string $tableName) : Table
     {
         $table = parent::listTableDetails($tableName);
 
diff --git a/lib/Doctrine/DBAL/Schema/SQLAnywhereSchemaManager.php b/lib/Doctrine/DBAL/Schema/SQLAnywhereSchemaManager.php
index df879a87ec4..bfb34b44a21 100644
--- a/lib/Doctrine/DBAL/Schema/SQLAnywhereSchemaManager.php
+++ b/lib/Doctrine/DBAL/Schema/SQLAnywhereSchemaManager.php
@@ -24,7 +24,7 @@ class SQLAnywhereSchemaManager extends AbstractSchemaManager
      *
      * @see startDatabase
      */
-    public function createDatabase($database)
+    public function createDatabase(string $database) : void
     {
         parent::createDatabase($database);
         $this->startDatabase($database);
@@ -39,29 +39,19 @@ public function createDatabase($database)
      *
      * @see stopDatabase
      */
-    public function dropDatabase($database)
+    public function dropDatabase(string $database) : void
     {
         $this->tryMethod('stopDatabase', $database);
         parent::dropDatabase($database);
     }
 
-    /**
-     * Starts a database.
-     *
-     * @param string $database The name of the database to start.
-     */
-    public function startDatabase($database)
+    public function startDatabase(string $database)
     {
         assert($this->_platform instanceof SQLAnywherePlatform);
         $this->_execSql($this->_platform->getStartDatabaseSQL($database));
     }
 
-    /**
-     * Stops a database.
-     *
-     * @param string $database The name of the database to stop.
-     */
-    public function stopDatabase($database)
+    public function stopDatabase(string $database)
     {
         assert($this->_platform instanceof SQLAnywherePlatform);
         $this->_execSql($this->_platform->getStopDatabaseSQL($database));
@@ -70,7 +60,7 @@ public function stopDatabase($database)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableDatabaseDefinition($database)
+    protected function _getPortableDatabaseDefinition(array $database) : string
     {
         return $database['name'];
     }
@@ -78,7 +68,7 @@ protected function _getPortableDatabaseDefinition($database)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableSequenceDefinition($sequence)
+    protected function _getPortableSequenceDefinition(array $sequence) : Sequence
     {
         return new Sequence($sequence['sequence_name'], $sequence['increment_by'], $sequence['start_with']);
     }
@@ -86,7 +76,7 @@ protected function _getPortableSequenceDefinition($sequence)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableColumnDefinition($tableColumn)
+    protected function _getPortableTableColumnDefinition(array $tableColumn) : Column
     {
         $type = $this->extractDoctrineTypeFromComment($tableColumn['comment'])
             ?? $this->_platform->getDoctrineTypeMapping($tableColumn['type']);
@@ -141,7 +131,7 @@ protected function _getPortableTableColumnDefinition($tableColumn)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableDefinition($table)
+    protected function _getPortableTableDefinition(array $table) : string
     {
         return $table['table_name'];
     }
@@ -149,7 +139,7 @@ protected function _getPortableTableDefinition($table)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableForeignKeyDefinition($tableForeignKey)
+    protected function _getPortableTableForeignKeyDefinition(array $tableForeignKey) : ForeignKeyConstraint
     {
         return new ForeignKeyConstraint(
             $tableForeignKey['local_columns'],
@@ -163,7 +153,7 @@ protected function _getPortableTableForeignKeyDefinition($tableForeignKey)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableForeignKeysList($tableForeignKeys)
+    protected function _getPortableTableForeignKeysList(array $tableForeignKeys) : array
     {
         $foreignKeys = [];
 
@@ -223,7 +213,7 @@ protected function _getPortableTableIndexesList(array $tableIndexRows, string $t
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableViewDefinition($view)
+    protected function _getPortableViewDefinition(array $view) : View
     {
         $definition = preg_replace('/^.*\s+as\s+SELECT(.*)/i', 'SELECT$1', $view['view_def']);
         assert(is_string($definition));
diff --git a/lib/Doctrine/DBAL/Schema/SQLServerSchemaManager.php b/lib/Doctrine/DBAL/Schema/SQLServerSchemaManager.php
index 978778dae29..50c1fa7506b 100644
--- a/lib/Doctrine/DBAL/Schema/SQLServerSchemaManager.php
+++ b/lib/Doctrine/DBAL/Schema/SQLServerSchemaManager.php
@@ -28,7 +28,7 @@ class SQLServerSchemaManager extends AbstractSchemaManager
     /**
      * {@inheritdoc}
      */
-    public function dropDatabase($database)
+    public function dropDatabase(string $database) : void
     {
         try {
             parent::dropDatabase($database);
@@ -57,7 +57,7 @@ public function dropDatabase($database)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableSequenceDefinition($sequence)
+    protected function _getPortableSequenceDefinition(array $sequence) : Sequence
     {
         return new Sequence($sequence['name'], (int) $sequence['increment'], (int) $sequence['start_value']);
     }
@@ -65,7 +65,7 @@ protected function _getPortableSequenceDefinition($sequence)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableColumnDefinition($tableColumn)
+    protected function _getPortableTableColumnDefinition(array $tableColumn) : Column
     {
         $dbType = strtok($tableColumn['type'], '(), ');
         assert(is_string($dbType));
@@ -159,7 +159,7 @@ private function parseDefaultExpression(string $value) : ?string
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableForeignKeysList($tableForeignKeys)
+    protected function _getPortableTableForeignKeysList(array $tableForeignKeys) : array
     {
         $foreignKeys = [];
 
@@ -201,7 +201,7 @@ protected function _getPortableTableIndexesList(array $tableIndexRows, string $t
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableForeignKeyDefinition($tableForeignKey)
+    protected function _getPortableTableForeignKeyDefinition(array $tableForeignKey) : ForeignKeyConstraint
     {
         return new ForeignKeyConstraint(
             $tableForeignKey['local_columns'],
@@ -215,7 +215,7 @@ protected function _getPortableTableForeignKeyDefinition($tableForeignKey)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableDefinition($table)
+    protected function _getPortableTableDefinition(array $table) : string
     {
         if (isset($table['schema_name']) && $table['schema_name'] !== 'dbo') {
             return $table['schema_name'] . '.' . $table['name'];
@@ -227,7 +227,7 @@ protected function _getPortableTableDefinition($table)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableDatabaseDefinition($database)
+    protected function _getPortableDatabaseDefinition(array $database) : string
     {
         return $database['name'];
     }
@@ -235,7 +235,7 @@ protected function _getPortableDatabaseDefinition($database)
     /**
      * {@inheritdoc}
      */
-    protected function getPortableNamespaceDefinition(array $namespace)
+    protected function getPortableNamespaceDefinition(array $namespace) : string
     {
         return $namespace['name'];
     }
@@ -243,7 +243,7 @@ protected function getPortableNamespaceDefinition(array $namespace)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableViewDefinition($view)
+    protected function _getPortableViewDefinition(array $view) : View
     {
         // @todo
         return new View($view['name'], '');
@@ -252,7 +252,7 @@ protected function _getPortableViewDefinition($view)
     /**
      * {@inheritdoc}
      */
-    public function listTableIndexes($table)
+    public function listTableIndexes(string $table) : array
     {
         $sql = $this->_platform->getListTableIndexesSQL($table, $this->_conn->getDatabase());
 
@@ -278,7 +278,7 @@ public function listTableIndexes($table)
     /**
      * {@inheritdoc}
      */
-    public function alterTable(TableDiff $tableDiff)
+    public function alterTable(TableDiff $tableDiff) : void
     {
         if (count($tableDiff->removedColumns) > 0) {
             foreach ($tableDiff->removedColumns as $col) {
@@ -300,13 +300,8 @@ public function alterTable(TableDiff $tableDiff)
 
     /**
      * Returns the SQL to retrieve the constraints for a given column.
-     *
-     * @param string $table
-     * @param string $column
-     *
-     * @return string
      */
-    private function getColumnConstraintSQL($table, $column)
+    private function getColumnConstraintSQL(string $table, string $column) : string
     {
         return "SELECT SysObjects.[Name]
             FROM SysObjects INNER JOIN (SELECT [Name],[ID] FROM SysObjects WHERE XType = 'U') AS Tab
@@ -321,12 +316,8 @@ private function getColumnConstraintSQL($table, $column)
      * Closes currently active connections on the given database.
      *
      * This is useful to force DROP DATABASE operations which could fail because of active connections.
-     *
-     * @param string $database The name of the database to close currently active connections for.
-     *
-     * @return void
      */
-    private function closeActiveDatabaseConnections($database)
+    private function closeActiveDatabaseConnections(string $database) : void
     {
         $database = new Identifier($database);
 
@@ -338,10 +329,7 @@ private function closeActiveDatabaseConnections($database)
         );
     }
 
-    /**
-     * @param string $tableName
-     */
-    public function listTableDetails($tableName) : Table
+    public function listTableDetails(string $tableName) : Table
     {
         $table = parent::listTableDetails($tableName);
 
diff --git a/lib/Doctrine/DBAL/Schema/Schema.php b/lib/Doctrine/DBAL/Schema/Schema.php
index b2fb2371abb..155578efb3c 100644
--- a/lib/Doctrine/DBAL/Schema/Schema.php
+++ b/lib/Doctrine/DBAL/Schema/Schema.php
@@ -47,23 +47,23 @@ class Schema extends AbstractAsset
     /**
      * The namespaces in this schema.
      *
-     * @var string[]
+     * @var array<string, string>
      */
     private $namespaces = [];
 
-    /** @var Table[] */
+    /** @var array<string, Table> */
     protected $_tables = [];
 
-    /** @var Sequence[] */
+    /** @var array<string, Sequence> */
     protected $_sequences = [];
 
     /** @var SchemaConfig */
-    protected $_schemaConfig = false;
+    protected $_schemaConfig;
 
     /**
-     * @param Table[]    $tables
-     * @param Sequence[] $sequences
-     * @param string[]   $namespaces
+     * @param array<Table>    $tables
+     * @param array<Sequence> $sequences
+     * @param array<string>   $namespaces
      */
     public function __construct(
         array $tables = [],
@@ -90,20 +90,15 @@ public function __construct(
         }
     }
 
-    /**
-     * @return bool
-     */
-    public function hasExplicitForeignKeyIndexes()
+    public function hasExplicitForeignKeyIndexes() : bool
     {
         return $this->_schemaConfig->hasExplicitForeignKeyIndexes();
     }
 
     /**
-     * @return void
-     *
      * @throws SchemaException
      */
-    protected function _addTable(Table $table)
+    protected function _addTable(Table $table) : void
     {
         $namespaceName = $table->getNamespaceName();
         $tableName     = $table->getFullQualifiedName($this->getName());
@@ -123,11 +118,9 @@ protected function _addTable(Table $table)
     }
 
     /**
-     * @return void
-     *
      * @throws SchemaException
      */
-    protected function _addSequence(Sequence $sequence)
+    protected function _addSequence(Sequence $sequence) : void
     {
         $namespaceName = $sequence->getNamespaceName();
         $seqName       = $sequence->getFullQualifiedName($this->getName());
@@ -148,9 +141,9 @@ protected function _addSequence(Sequence $sequence)
     /**
      * Returns the namespaces of this schema.
      *
-     * @return string[] A list of namespace names.
+     * @return array<string, string> A list of namespace names.
      */
-    public function getNamespaces()
+    public function getNamespaces() : array
     {
         return $this->namespaces;
     }
@@ -158,21 +151,17 @@ public function getNamespaces()
     /**
      * Gets all tables of this schema.
      *
-     * @return Table[]
+     * @return array<string, Table>
      */
-    public function getTables()
+    public function getTables() : array
     {
         return $this->_tables;
     }
 
     /**
-     * @param string $tableName
-     *
-     * @return Table
-     *
      * @throws SchemaException
      */
-    public function getTable($tableName)
+    public function getTable(string $tableName) : Table
     {
         $tableName = $this->getFullQualifiedAssetName($tableName);
         if (! isset($this->_tables[$tableName])) {
@@ -182,12 +171,7 @@ public function getTable($tableName)
         return $this->_tables[$tableName];
     }
 
-    /**
-     * @param string $name
-     *
-     * @return string
-     */
-    private function getFullQualifiedAssetName($name)
+    private function getFullQualifiedAssetName(string $name) : string
     {
         $name = $this->getUnquotedAssetName($name);
 
@@ -200,12 +184,8 @@ private function getFullQualifiedAssetName($name)
 
     /**
      * Returns the unquoted representation of a given asset name.
-     *
-     * @param string $assetName Quoted or unquoted representation of an asset name.
-     *
-     * @return string
      */
-    private function getUnquotedAssetName($assetName)
+    private function getUnquotedAssetName(string $assetName) : string
     {
         if ($this->isIdentifierQuoted($assetName)) {
             return $this->trimQuotes($assetName);
@@ -216,12 +196,8 @@ private function getUnquotedAssetName($assetName)
 
     /**
      * Does this schema have a namespace with the given name?
-     *
-     * @param string $namespaceName
-     *
-     * @return bool
      */
-    public function hasNamespace($namespaceName)
+    public function hasNamespace(string $namespaceName) : bool
     {
         $namespaceName = strtolower($this->getUnquotedAssetName($namespaceName));
 
@@ -230,12 +206,8 @@ public function hasNamespace($namespaceName)
 
     /**
      * Does this schema have a table with the given name?
-     *
-     * @param string $tableName
-     *
-     * @return bool
      */
-    public function hasTable($tableName)
+    public function hasTable(string $tableName) : bool
     {
         $tableName = $this->getFullQualifiedAssetName($tableName);
 
@@ -245,19 +217,14 @@ public function hasTable($tableName)
     /**
      * Gets all table names, prefixed with a schema name, even the default one if present.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getTableNames()
+    public function getTableNames() : array
     {
         return array_keys($this->_tables);
     }
 
-    /**
-     * @param string $sequenceName
-     *
-     * @return bool
-     */
-    public function hasSequence($sequenceName)
+    public function hasSequence(string $sequenceName) : bool
     {
         $sequenceName = $this->getFullQualifiedAssetName($sequenceName);
 
@@ -265,13 +232,9 @@ public function hasSequence($sequenceName)
     }
 
     /**
-     * @param string $sequenceName
-     *
-     * @return Sequence
-     *
      * @throws SchemaException
      */
-    public function getSequence($sequenceName)
+    public function getSequence(string $sequenceName) : Sequence
     {
         $sequenceName = $this->getFullQualifiedAssetName($sequenceName);
         if (! $this->hasSequence($sequenceName)) {
@@ -282,9 +245,9 @@ public function getSequence($sequenceName)
     }
 
     /**
-     * @return Sequence[]
+     * @return array<string, Sequence>
      */
-    public function getSequences()
+    public function getSequences() : array
     {
         return $this->_sequences;
     }
@@ -292,13 +255,11 @@ public function getSequences()
     /**
      * Creates a new namespace.
      *
-     * @param string $namespaceName The name of the namespace to create.
-     *
-     * @return \Doctrine\DBAL\Schema\Schema This schema instance.
+     * @return $this
      *
      * @throws SchemaException
      */
-    public function createNamespace($namespaceName)
+    public function createNamespace(string $namespaceName) : self
     {
         $unquotedNamespaceName = strtolower($this->getUnquotedAssetName($namespaceName));
 
@@ -313,12 +274,8 @@ public function createNamespace($namespaceName)
 
     /**
      * Creates a new table.
-     *
-     * @param string $tableName
-     *
-     * @return Table
      */
-    public function createTable($tableName)
+    public function createTable(string $tableName) : Table
     {
         $table = new Table($tableName);
         $this->_addTable($table);
@@ -333,12 +290,9 @@ public function createTable($tableName)
     /**
      * Renames a table.
      *
-     * @param string $oldTableName
-     * @param string $newTableName
-     *
-     * @return \Doctrine\DBAL\Schema\Schema
+     * @return $this
      */
-    public function renameTable($oldTableName, $newTableName)
+    public function renameTable(string $oldTableName, string $newTableName) : self
     {
         $table = $this->getTable($oldTableName);
         $table->_setName($newTableName);
@@ -352,11 +306,9 @@ public function renameTable($oldTableName, $newTableName)
     /**
      * Drops a table from the schema.
      *
-     * @param string $tableName
-     *
-     * @return \Doctrine\DBAL\Schema\Schema
+     * @return $this
      */
-    public function dropTable($tableName)
+    public function dropTable(string $tableName) : self
     {
         $tableName = $this->getFullQualifiedAssetName($tableName);
         $this->getTable($tableName);
@@ -367,14 +319,8 @@ public function dropTable($tableName)
 
     /**
      * Creates a new sequence.
-     *
-     * @param string $sequenceName
-     * @param int    $allocationSize
-     * @param int    $initialValue
-     *
-     * @return Sequence
      */
-    public function createSequence($sequenceName, $allocationSize = 1, $initialValue = 1)
+    public function createSequence(string $sequenceName, int $allocationSize = 1, int $initialValue = 1) : Sequence
     {
         $seq = new Sequence($sequenceName, $allocationSize, $initialValue);
         $this->_addSequence($seq);
@@ -383,11 +329,9 @@ public function createSequence($sequenceName, $allocationSize = 1, $initialValue
     }
 
     /**
-     * @param string $sequenceName
-     *
-     * @return \Doctrine\DBAL\Schema\Schema
+     * @return $this
      */
-    public function dropSequence($sequenceName)
+    public function dropSequence(string $sequenceName) : self
     {
         $sequenceName = $this->getFullQualifiedAssetName($sequenceName);
         unset($this->_sequences[$sequenceName]);
@@ -398,9 +342,9 @@ public function dropSequence($sequenceName)
     /**
      * Returns an array of necessary SQL queries to create the schema on the given platform.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function toSql(AbstractPlatform $platform)
+    public function toSql(AbstractPlatform $platform) : array
     {
         $sqlCollector = new CreateSchemaSqlCollector($platform);
         $this->visit($sqlCollector);
@@ -411,9 +355,9 @@ public function toSql(AbstractPlatform $platform)
     /**
      * Return an array of necessary SQL queries to drop the schema on the given platform.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function toDropSql(AbstractPlatform $platform)
+    public function toDropSql(AbstractPlatform $platform) : array
     {
         $dropSqlCollector = new DropSchemaSqlCollector($platform);
         $this->visit($dropSqlCollector);
@@ -422,9 +366,9 @@ public function toDropSql(AbstractPlatform $platform)
     }
 
     /**
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getMigrateToSql(Schema $toSchema, AbstractPlatform $platform)
+    public function getMigrateToSql(Schema $toSchema, AbstractPlatform $platform) : array
     {
         $comparator = new Comparator();
         $schemaDiff = $comparator->compare($this, $toSchema);
@@ -433,9 +377,9 @@ public function getMigrateToSql(Schema $toSchema, AbstractPlatform $platform)
     }
 
     /**
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getMigrateFromSql(Schema $fromSchema, AbstractPlatform $platform)
+    public function getMigrateFromSql(Schema $fromSchema, AbstractPlatform $platform) : array
     {
         $comparator = new Comparator();
         $schemaDiff = $comparator->compare($fromSchema, $this);
@@ -443,10 +387,7 @@ public function getMigrateFromSql(Schema $fromSchema, AbstractPlatform $platform
         return $schemaDiff->toSql($platform);
     }
 
-    /**
-     * @return void
-     */
-    public function visit(Visitor $visitor)
+    public function visit(Visitor $visitor) : void
     {
         $visitor->acceptSchema($this);
 
diff --git a/lib/Doctrine/DBAL/Schema/SchemaConfig.php b/lib/Doctrine/DBAL/Schema/SchemaConfig.php
index e3a2f36b0b4..ef2dc0b91a5 100644
--- a/lib/Doctrine/DBAL/Schema/SchemaConfig.php
+++ b/lib/Doctrine/DBAL/Schema/SchemaConfig.php
@@ -15,66 +15,44 @@ class SchemaConfig
     /** @var int */
     protected $maxIdentifierLength = 63;
 
-    /** @var string */
+    /** @var string|null */
     protected $name;
 
-    /** @var mixed[] */
+    /** @var array<string, mixed> */
     protected $defaultTableOptions = [];
 
-    /**
-     * @return bool
-     */
-    public function hasExplicitForeignKeyIndexes()
+    public function hasExplicitForeignKeyIndexes() : bool
     {
         return $this->hasExplicitForeignKeyIndexes;
     }
 
-    /**
-     * @param bool $flag
-     *
-     * @return void
-     */
-    public function setExplicitForeignKeyIndexes($flag)
+    public function setExplicitForeignKeyIndexes(bool $flag) : void
     {
-        $this->hasExplicitForeignKeyIndexes = (bool) $flag;
+        $this->hasExplicitForeignKeyIndexes = $flag;
     }
 
-    /**
-     * @param int $length
-     *
-     * @return void
-     */
-    public function setMaxIdentifierLength($length)
+    public function setMaxIdentifierLength(int $length) : void
     {
-        $this->maxIdentifierLength = (int) $length;
+        $this->maxIdentifierLength = $length;
     }
 
-    /**
-     * @return int
-     */
-    public function getMaxIdentifierLength()
+    public function getMaxIdentifierLength() : int
     {
         return $this->maxIdentifierLength;
     }
 
     /**
      * Gets the default namespace of schema objects.
-     *
-     * @return string
      */
-    public function getName()
+    public function getName() : ?string
     {
         return $this->name;
     }
 
     /**
      * Sets the default namespace name of schema objects.
-     *
-     * @param string $name The value to set.
-     *
-     * @return void
      */
-    public function setName($name)
+    public function setName(string $name) : void
     {
         $this->name = $name;
     }
@@ -83,19 +61,17 @@ public function setName($name)
      * Gets the default options that are passed to Table instances created with
      * Schema#createTable().
      *
-     * @return mixed[]
+     * @return array<string, mixed>
      */
-    public function getDefaultTableOptions()
+    public function getDefaultTableOptions() : array
     {
         return $this->defaultTableOptions;
     }
 
     /**
-     * @param mixed[] $defaultTableOptions
-     *
-     * @return void
+     * @param array<string, mixed> $defaultTableOptions
      */
-    public function setDefaultTableOptions(array $defaultTableOptions)
+    public function setDefaultTableOptions(array $defaultTableOptions) : void
     {
         $this->defaultTableOptions = $defaultTableOptions;
     }
diff --git a/lib/Doctrine/DBAL/Schema/SchemaDiff.php b/lib/Doctrine/DBAL/Schema/SchemaDiff.php
index 97033eeeebb..6a572f3ba8e 100644
--- a/lib/Doctrine/DBAL/Schema/SchemaDiff.php
+++ b/lib/Doctrine/DBAL/Schema/SchemaDiff.php
@@ -18,58 +18,58 @@ class SchemaDiff
     /**
      * All added namespaces.
      *
-     * @var string[]
+     * @var array<string, string>
      */
     public $newNamespaces = [];
 
     /**
      * All removed namespaces.
      *
-     * @var string[]
+     * @var array<string, string>
      */
     public $removedNamespaces = [];
 
     /**
      * All added tables.
      *
-     * @var Table[]
+     * @var array<string, Table>
      */
     public $newTables = [];
 
     /**
      * All changed tables.
      *
-     * @var TableDiff[]
+     * @var array<string, TableDiff>
      */
     public $changedTables = [];
 
     /**
      * All removed tables.
      *
-     * @var Table[]
+     * @var array<string, Table>
      */
     public $removedTables = [];
 
-    /** @var Sequence[] */
+    /** @var array<int, Sequence> */
     public $newSequences = [];
 
-    /** @var Sequence[] */
+    /** @var array<int, Sequence> */
     public $changedSequences = [];
 
-    /** @var Sequence[] */
+    /** @var array<int, Sequence> */
     public $removedSequences = [];
 
-    /** @var ForeignKeyConstraint[] */
+    /** @var array<string|int, ForeignKeyConstraint> */
     public $orphanedForeignKeys = [];
 
     /**
      * Constructs an SchemaDiff object.
      *
-     * @param Table[]     $newTables
-     * @param TableDiff[] $changedTables
-     * @param Table[]     $removedTables
+     * @param array<string, Table>     $newTables
+     * @param array<string, TableDiff> $changedTables
+     * @param array<string, Table>     $removedTables
      */
-    public function __construct($newTables = [], $changedTables = [], $removedTables = [], ?Schema $fromSchema = null)
+    public function __construct(array $newTables = [], array $changedTables = [], array $removedTables = [], ?Schema $fromSchema = null)
     {
         $this->newTables     = $newTables;
         $this->changedTables = $changedTables;
@@ -86,27 +86,25 @@ public function __construct($newTables = [], $changedTables = [], $removedTables
      *
      * This way it is ensured that assets are deleted which might not be relevant to the metadata schema at all.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function toSaveSql(AbstractPlatform $platform)
+    public function toSaveSql(AbstractPlatform $platform) : array
     {
         return $this->_toSql($platform, true);
     }
 
     /**
-     * @return string[]
+     * @return array<int, string>
      */
-    public function toSql(AbstractPlatform $platform)
+    public function toSql(AbstractPlatform $platform) : array
     {
         return $this->_toSql($platform, false);
     }
 
     /**
-     * @param bool $saveMode
-     *
-     * @return string[]
+     * @return array<int, string>
      */
-    protected function _toSql(AbstractPlatform $platform, $saveMode = false)
+    protected function _toSql(AbstractPlatform $platform, bool $saveMode = false) : array
     {
         $sql = [];
 
diff --git a/lib/Doctrine/DBAL/Schema/Sequence.php b/lib/Doctrine/DBAL/Schema/Sequence.php
index 89147984136..86989250d2d 100644
--- a/lib/Doctrine/DBAL/Schema/Sequence.php
+++ b/lib/Doctrine/DBAL/Schema/Sequence.php
@@ -22,13 +22,7 @@ class Sequence extends AbstractAsset
     /** @var int|null */
     protected $cache = null;
 
-    /**
-     * @param string   $name
-     * @param int      $allocationSize
-     * @param int      $initialValue
-     * @param int|null $cache
-     */
-    public function __construct($name, $allocationSize = 1, $initialValue = 1, $cache = null)
+    public function __construct(string $name, int $allocationSize = 1, int $initialValue = 1, ?int $cache = null)
     {
         $this->_setName($name);
         $this->setAllocationSize($allocationSize);
@@ -36,60 +30,36 @@ public function __construct($name, $allocationSize = 1, $initialValue = 1, $cach
         $this->cache = $cache;
     }
 
-    /**
-     * @return int
-     */
-    public function getAllocationSize()
+    public function getAllocationSize() : int
     {
         return $this->allocationSize;
     }
 
-    /**
-     * @return int
-     */
-    public function getInitialValue()
+    public function getInitialValue() : int
     {
         return $this->initialValue;
     }
 
-    /**
-     * @return int|null
-     */
-    public function getCache()
+    public function getCache() : ?int
     {
         return $this->cache;
     }
 
-    /**
-     * @param int $allocationSize
-     *
-     * @return \Doctrine\DBAL\Schema\Sequence
-     */
-    public function setAllocationSize($allocationSize)
+    public function setAllocationSize(int $allocationSize) : self
     {
-        $this->allocationSize = (int) $allocationSize ?: 1;
+        $this->allocationSize = $allocationSize;
 
         return $this;
     }
 
-    /**
-     * @param int $initialValue
-     *
-     * @return \Doctrine\DBAL\Schema\Sequence
-     */
-    public function setInitialValue($initialValue)
+    public function setInitialValue(int $initialValue) : self
     {
-        $this->initialValue = (int) $initialValue ?: 1;
+        $this->initialValue = $initialValue;
 
         return $this;
     }
 
-    /**
-     * @param int $cache
-     *
-     * @return \Doctrine\DBAL\Schema\Sequence
-     */
-    public function setCache($cache)
+    public function setCache(int $cache) : self
     {
         $this->cache = $cache;
 
@@ -101,10 +71,8 @@ public function setCache($cache)
      *
      * This is used inside the comparator to not report sequences as missing,
      * when the "from" schema implicitly creates the sequences.
-     *
-     * @return bool
      */
-    public function isAutoIncrementsFor(Table $table)
+    public function isAutoIncrementsFor(Table $table) : bool
     {
         $primaryKey = $table->getPrimaryKey();
 
@@ -131,10 +99,7 @@ public function isAutoIncrementsFor(Table $table)
         return $tableSequenceName === $sequenceName;
     }
 
-    /**
-     * @return void
-     */
-    public function visit(Visitor $visitor)
+    public function visit(Visitor $visitor) : void
     {
         $visitor->acceptSequence($this);
     }
diff --git a/lib/Doctrine/DBAL/Schema/SqliteSchemaManager.php b/lib/Doctrine/DBAL/Schema/SqliteSchemaManager.php
index e14b78be5ee..0464e739732 100644
--- a/lib/Doctrine/DBAL/Schema/SqliteSchemaManager.php
+++ b/lib/Doctrine/DBAL/Schema/SqliteSchemaManager.php
@@ -4,7 +4,6 @@
 
 namespace Doctrine\DBAL\Schema;
 
-use Doctrine\DBAL\DBALException;
 use Doctrine\DBAL\DriverManager;
 use Doctrine\DBAL\FetchMode;
 use Doctrine\DBAL\Types\StringType;
@@ -16,6 +15,7 @@
 use function array_values;
 use function count;
 use function file_exists;
+use function is_string;
 use function preg_match;
 use function preg_match_all;
 use function preg_quote;
@@ -37,7 +37,7 @@ class SqliteSchemaManager extends AbstractSchemaManager
     /**
      * {@inheritdoc}
      */
-    public function dropDatabase($database)
+    public function dropDatabase(string $database) : void
     {
         if (! file_exists($database)) {
             return;
@@ -49,7 +49,7 @@ public function dropDatabase($database)
     /**
      * {@inheritdoc}
      */
-    public function createDatabase($database)
+    public function createDatabase(string $database) : void
     {
         $params  = $this->_conn->getParams();
         $driver  = $params['driver'];
@@ -65,7 +65,7 @@ public function createDatabase($database)
     /**
      * {@inheritdoc}
      */
-    public function renameTable($name, $newName)
+    public function renameTable(string $name, string $newName) : void
     {
         $tableDiff            = new TableDiff($name);
         $tableDiff->fromTable = $this->listTableDetails($name);
@@ -76,9 +76,12 @@ public function renameTable($name, $newName)
     /**
      * {@inheritdoc}
      */
-    public function createForeignKey(ForeignKeyConstraint $foreignKey, $table)
+    public function createForeignKey(ForeignKeyConstraint $foreignKey, $table) : void
     {
-        $tableDiff                     = $this->getTableDiffForAlterForeignKey($table);
+        $table = $this->ensureTable($table);
+
+        $tableDiff = $this->getTableDiffForAlterForeignKey($table);
+
         $tableDiff->addedForeignKeys[] = $foreignKey;
 
         $this->alterTable($tableDiff);
@@ -87,9 +90,12 @@ public function createForeignKey(ForeignKeyConstraint $foreignKey, $table)
     /**
      * {@inheritdoc}
      */
-    public function dropAndCreateForeignKey(ForeignKeyConstraint $foreignKey, $table)
+    public function dropAndCreateForeignKey(ForeignKeyConstraint $foreignKey, $table) : void
     {
-        $tableDiff                       = $this->getTableDiffForAlterForeignKey($table);
+        $table = $this->ensureTable($table);
+
+        $tableDiff = $this->getTableDiffForAlterForeignKey($table);
+
         $tableDiff->changedForeignKeys[] = $foreignKey;
 
         $this->alterTable($tableDiff);
@@ -98,10 +104,17 @@ public function dropAndCreateForeignKey(ForeignKeyConstraint $foreignKey, $table
     /**
      * {@inheritdoc}
      */
-    public function dropForeignKey($foreignKey, $table)
+    public function dropForeignKey($foreignKey, $table) : void
     {
-        $tableDiff                       = $this->getTableDiffForAlterForeignKey($table);
-        $tableDiff->removedForeignKeys[] = $foreignKey;
+        $table = $this->ensureTable($table);
+
+        $tableDiff = $this->getTableDiffForAlterForeignKey($table);
+
+        if (is_string($foreignKey)) {
+            $tableDiff->removedForeignKeys[] = $table->getForeignKey($foreignKey);
+        } else {
+            $tableDiff->removedForeignKeys[] = $foreignKey;
+        }
 
         $this->alterTable($tableDiff);
     }
@@ -109,7 +122,7 @@ public function dropForeignKey($foreignKey, $table)
     /**
      * {@inheritdoc}
      */
-    public function listTableForeignKeys($table, $database = null)
+    public function listTableForeignKeys(string $table, ?string $database = null) : array
     {
         if ($database === null) {
             $database = $this->_conn->getDatabase();
@@ -154,7 +167,7 @@ public function listTableForeignKeys($table, $database = null)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableDefinition($table)
+    protected function _getPortableTableDefinition(array $table) : string
     {
         return $table['name'];
     }
@@ -226,18 +239,7 @@ protected function _getPortableTableIndexesList(array $tableIndexRows, string $t
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableIndexDefinition($tableIndex)
-    {
-        return [
-            'name' => $tableIndex['name'],
-            'unique' => (bool) $tableIndex['unique'],
-        ];
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    protected function _getPortableTableColumnList($table, $database, $tableColumns)
+    protected function _getPortableTableColumnList(string $table, string $database, array $tableColumns) : array
     {
         $list = parent::_getPortableTableColumnList($table, $database, $tableColumns);
 
@@ -295,7 +297,7 @@ protected function _getPortableTableColumnList($table, $database, $tableColumns)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableColumnDefinition($tableColumn)
+    protected function _getPortableTableColumnDefinition(array $tableColumn) : Column
     {
         preg_match('/^([^()]*)\\s*(\\(((\\d+)(,\\s*(\\d+))?)\\))?/', $tableColumn['type'], $matches);
 
@@ -357,7 +359,7 @@ protected function _getPortableTableColumnDefinition($tableColumn)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableViewDefinition($view)
+    protected function _getPortableViewDefinition(array $view) : View
     {
         return new View($view['name'], $view['sql']);
     }
@@ -365,7 +367,7 @@ protected function _getPortableViewDefinition($view)
     /**
      * {@inheritdoc}
      */
-    protected function _getPortableTableForeignKeysList($tableForeignKeys)
+    protected function _getPortableTableForeignKeysList(array $tableForeignKeys) : array
     {
         $list = [];
         foreach ($tableForeignKeys as $value) {
@@ -413,31 +415,26 @@ protected function _getPortableTableForeignKeysList($tableForeignKeys)
         return $result;
     }
 
-    /**
-     * @param Table|string $table
-     *
-     * @return TableDiff
-     *
-     * @throws DBALException
-     */
-    private function getTableDiffForAlterForeignKey($table)
+    private function getTableDiffForAlterForeignKey(Table $table) : TableDiff
     {
-        if (! $table instanceof Table) {
-            $tableDetails = $this->tryMethod('listTableDetails', $table);
-
-            if ($tableDetails === false) {
-                throw new DBALException(sprintf('Sqlite schema manager requires to modify foreign keys table definition "%s".', $table));
-            }
-
-            $table = $tableDetails;
-        }
-
         $tableDiff            = new TableDiff($table->getName());
         $tableDiff->fromTable = $table;
 
         return $tableDiff;
     }
 
+    /**
+     * @param string|Table $table
+     */
+    private function ensureTable($table) : Table
+    {
+        if (is_string($table)) {
+            $table = $this->listTableDetails($table);
+        }
+
+        return $table;
+    }
+
     private function parseColumnCollationFromSQL(string $column, string $sql) : ?string
     {
         $pattern = '{(?:\W' . preg_quote($column) . '\W|\W' . preg_quote($this->_platform->quoteSingleIdentifier($column))
@@ -503,10 +500,7 @@ private function getCreateTableSQL(string $table) : ?string
         ) ?: null;
     }
 
-    /**
-     * @param string $tableName
-     */
-    public function listTableDetails($tableName) : Table
+    public function listTableDetails(string $tableName) : Table
     {
         $table = parent::listTableDetails($tableName);
 
diff --git a/lib/Doctrine/DBAL/Schema/Synchronizer/AbstractSchemaSynchronizer.php b/lib/Doctrine/DBAL/Schema/Synchronizer/AbstractSchemaSynchronizer.php
index 74dce854098..3ec2ebd649f 100644
--- a/lib/Doctrine/DBAL/Schema/Synchronizer/AbstractSchemaSynchronizer.php
+++ b/lib/Doctrine/DBAL/Schema/Synchronizer/AbstractSchemaSynchronizer.php
@@ -21,9 +21,9 @@ public function __construct(Connection $conn)
     }
 
     /**
-     * @param string[] $sql
+     * @param array<int, string> $sql
      */
-    protected function processSqlSafely(array $sql)
+    protected function processSqlSafely(array $sql) : void
     {
         foreach ($sql as $s) {
             try {
@@ -34,9 +34,9 @@ protected function processSqlSafely(array $sql)
     }
 
     /**
-     * @param string[] $sql
+     * @param array<int, string> $sql
      */
-    protected function processSql(array $sql)
+    protected function processSql(array $sql) : void
     {
         foreach ($sql as $s) {
             $this->conn->exec($s);
diff --git a/lib/Doctrine/DBAL/Schema/Synchronizer/SchemaSynchronizer.php b/lib/Doctrine/DBAL/Schema/Synchronizer/SchemaSynchronizer.php
index 8e0eb117c4f..58ab02e67d5 100644
--- a/lib/Doctrine/DBAL/Schema/Synchronizer/SchemaSynchronizer.php
+++ b/lib/Doctrine/DBAL/Schema/Synchronizer/SchemaSynchronizer.php
@@ -15,60 +15,48 @@ interface SchemaSynchronizer
     /**
      * Gets the SQL statements that can be executed to create the schema.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getCreateSchema(Schema $createSchema);
+    public function getCreateSchema(Schema $createSchema) : array;
 
     /**
      * Gets the SQL Statements to update given schema with the underlying db.
      *
-     * @param bool $noDrops
-     *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getUpdateSchema(Schema $toSchema, $noDrops = false);
+    public function getUpdateSchema(Schema $toSchema, bool $noDrops = false) : array;
 
     /**
      * Gets the SQL Statements to drop the given schema from underlying db.
      *
      * @return string[]
      */
-    public function getDropSchema(Schema $dropSchema);
+    public function getDropSchema(Schema $dropSchema) : array;
 
     /**
      * Gets the SQL statements to drop all schema assets from underlying db.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getDropAllSchema();
+    public function getDropAllSchema() : array;
 
     /**
      * Creates the Schema.
-     *
-     * @return void
      */
-    public function createSchema(Schema $createSchema);
+    public function createSchema(Schema $createSchema) : void;
 
     /**
      * Updates the Schema to new schema version.
-     *
-     * @param bool $noDrops
-     *
-     * @return void
      */
-    public function updateSchema(Schema $toSchema, $noDrops = false);
+    public function updateSchema(Schema $toSchema, bool $noDrops = false) : void;
 
     /**
      * Drops the given database schema from the underlying db.
-     *
-     * @return void
      */
-    public function dropSchema(Schema $dropSchema);
+    public function dropSchema(Schema $dropSchema) : void;
 
     /**
      * Drops all assets from the underlying db.
-     *
-     * @return void
      */
-    public function dropAllSchema();
+    public function dropAllSchema() : void;
 }
diff --git a/lib/Doctrine/DBAL/Schema/Synchronizer/SingleDatabaseSynchronizer.php b/lib/Doctrine/DBAL/Schema/Synchronizer/SingleDatabaseSynchronizer.php
index 83abc250596..605add99cc6 100644
--- a/lib/Doctrine/DBAL/Schema/Synchronizer/SingleDatabaseSynchronizer.php
+++ b/lib/Doctrine/DBAL/Schema/Synchronizer/SingleDatabaseSynchronizer.php
@@ -28,7 +28,7 @@ public function __construct(Connection $conn)
     /**
      * {@inheritdoc}
      */
-    public function getCreateSchema(Schema $createSchema)
+    public function getCreateSchema(Schema $createSchema) : array
     {
         return $createSchema->toSql($this->platform);
     }
@@ -36,7 +36,7 @@ public function getCreateSchema(Schema $createSchema)
     /**
      * {@inheritdoc}
      */
-    public function getUpdateSchema(Schema $toSchema, $noDrops = false)
+    public function getUpdateSchema(Schema $toSchema, bool $noDrops = false) : array
     {
         $comparator = new Comparator();
         $sm         = $this->conn->getSchemaManager();
@@ -54,7 +54,7 @@ public function getUpdateSchema(Schema $toSchema, $noDrops = false)
     /**
      * {@inheritdoc}
      */
-    public function getDropSchema(Schema $dropSchema)
+    public function getDropSchema(Schema $dropSchema) : array
     {
         $visitor = new DropSchemaSqlCollector($this->platform);
         $sm      = $this->conn->getSchemaManager();
@@ -114,7 +114,7 @@ public function getDropSchema(Schema $dropSchema)
     /**
      * {@inheritdoc}
      */
-    public function getDropAllSchema()
+    public function getDropAllSchema() : array
     {
         $sm      = $this->conn->getSchemaManager();
         $visitor = new DropSchemaSqlCollector($this->platform);
@@ -128,7 +128,7 @@ public function getDropAllSchema()
     /**
      * {@inheritdoc}
      */
-    public function createSchema(Schema $createSchema)
+    public function createSchema(Schema $createSchema) : void
     {
         $this->processSql($this->getCreateSchema($createSchema));
     }
@@ -136,7 +136,7 @@ public function createSchema(Schema $createSchema)
     /**
      * {@inheritdoc}
      */
-    public function updateSchema(Schema $toSchema, $noDrops = false)
+    public function updateSchema(Schema $toSchema, bool $noDrops = false) : void
     {
         $this->processSql($this->getUpdateSchema($toSchema, $noDrops));
     }
@@ -144,7 +144,7 @@ public function updateSchema(Schema $toSchema, $noDrops = false)
     /**
      * {@inheritdoc}
      */
-    public function dropSchema(Schema $dropSchema)
+    public function dropSchema(Schema $dropSchema) : void
     {
         $this->processSqlSafely($this->getDropSchema($dropSchema));
     }
@@ -152,7 +152,7 @@ public function dropSchema(Schema $dropSchema)
     /**
      * {@inheritdoc}
      */
-    public function dropAllSchema()
+    public function dropAllSchema() : void
     {
         $this->processSql($this->getDropAllSchema());
     }
diff --git a/lib/Doctrine/DBAL/Schema/Table.php b/lib/Doctrine/DBAL/Schema/Table.php
index f9367ffc1a6..99a742a6010 100644
--- a/lib/Doctrine/DBAL/Schema/Table.php
+++ b/lib/Doctrine/DBAL/Schema/Table.php
@@ -59,17 +59,16 @@ class Table extends AbstractAsset
     protected $_schemaConfig = null;
 
     /**
-     * @param string                 $tableName
-     * @param Column[]               $columns
-     * @param Index[]                $indexes
-     * @param UniqueConstraint[]     $uniqueConstraints
-     * @param ForeignKeyConstraint[] $fkConstraints
-     * @param mixed[]                $options
+     * @param array<Column>               $columns
+     * @param array<Index>                $indexes
+     * @param array<UniqueConstraint>     $uniqueConstraints
+     * @param array<ForeignKeyConstraint> $fkConstraints
+     * @param array<string, mixed>        $options
      *
      * @throws DBALException
      */
     public function __construct(
-        $tableName,
+        string $tableName,
         array $columns = [],
         array $indexes = [],
         array $uniqueConstraints = [],
@@ -101,10 +100,7 @@ public function __construct(
         $this->_options = array_merge($this->_options, $options);
     }
 
-    /**
-     * @return void
-     */
-    public function setSchemaConfig(SchemaConfig $schemaConfig)
+    public function setSchemaConfig(SchemaConfig $schemaConfig) : void
     {
         $this->_schemaConfig = $schemaConfig;
     }
@@ -112,12 +108,9 @@ public function setSchemaConfig(SchemaConfig $schemaConfig)
     /**
      * Sets the Primary Key.
      *
-     * @param string[]     $columnNames
-     * @param string|false $indexName
-     *
-     * @return self
+     * @param array<int, string> $columnNames
      */
-    public function setPrimaryKey(array $columnNames, $indexName = false)
+    public function setPrimaryKey(array $columnNames, ?string $indexName = null) : self
     {
         $this->_addIndex($this->_createIndex($columnNames, $indexName ?: 'primary', true, true));
 
@@ -130,14 +123,11 @@ public function setPrimaryKey(array $columnNames, $indexName = false)
     }
 
     /**
-     * @param mixed[]     $columnNames
-     * @param string|null $indexName
-     * @param string[]    $flags
-     * @param mixed[]     $options
-     *
-     * @return self
+     * @param array<int, string>   $columnNames
+     * @param array<int, string>   $flags
+     * @param array<string, mixed> $options
      */
-    public function addUniqueConstraint(array $columnNames, $indexName = null, array $flags = [], array $options = [])
+    public function addUniqueConstraint(array $columnNames, ?string $indexName = null, array $flags = [], array $options = []) : self
     {
         if ($indexName === null) {
             $indexName = $this->_generateIdentifierName(
@@ -151,14 +141,11 @@ public function addUniqueConstraint(array $columnNames, $indexName = null, array
     }
 
     /**
-     * @param string[]    $columnNames
-     * @param string|null $indexName
-     * @param string[]    $flags
-     * @param mixed[]     $options
-     *
-     * @return self
+     * @param array<int, string>   $columnNames
+     * @param array<int, string>   $flags
+     * @param array<string, mixed> $options
      */
-    public function addIndex(array $columnNames, $indexName = null, array $flags = [], array $options = [])
+    public function addIndex(array $columnNames, ?string $indexName = null, array $flags = [], array $options = []) : self
     {
         if ($indexName === null) {
             $indexName = $this->_generateIdentifierName(
@@ -173,10 +160,8 @@ public function addIndex(array $columnNames, $indexName = null, array $flags = [
 
     /**
      * Drops the primary key from this table.
-     *
-     * @return void
      */
-    public function dropPrimaryKey()
+    public function dropPrimaryKey() : void
     {
         $this->dropIndex($this->_primaryKeyName);
         $this->_primaryKeyName = false;
@@ -185,13 +170,9 @@ public function dropPrimaryKey()
     /**
      * Drops an index from this table.
      *
-     * @param string $indexName The index name.
-     *
-     * @return void
-     *
      * @throws SchemaException If the index does not exist.
      */
-    public function dropIndex($indexName)
+    public function dropIndex(string $indexName) : void
     {
         $indexName = $this->normalizeIdentifier($indexName);
 
@@ -203,13 +184,10 @@ public function dropIndex($indexName)
     }
 
     /**
-     * @param string[]    $columnNames
-     * @param string|null $indexName
-     * @param mixed[]     $options
-     *
-     * @return self
+     * @param array<int, string>   $columnNames
+     * @param array<string, mixed> $options
      */
-    public function addUniqueIndex(array $columnNames, $indexName = null, array $options = [])
+    public function addUniqueIndex(array $columnNames, ?string $indexName = null, array $options = []) : self
     {
         if ($indexName === null) {
             $indexName = $this->_generateIdentifierName(
@@ -229,12 +207,10 @@ public function addUniqueIndex(array $columnNames, $indexName = null, array $opt
      * @param string|null $newIndexName The name of the index to rename to.
      *                                  If null is given, the index name will be auto-generated.
      *
-     * @return self This table instance.
-     *
      * @throws SchemaException If no index exists for the given current name
      *                         or if an index with the given new name already exists on this table.
      */
-    public function renameIndex($oldIndexName, $newIndexName = null)
+    public function renameIndex(string $oldIndexName, ?string $newIndexName = null) : self
     {
         $oldIndexName           = $this->normalizeIdentifier($oldIndexName);
         $normalizedNewIndexName = $this->normalizeIdentifier($newIndexName);
@@ -256,7 +232,7 @@ public function renameIndex($oldIndexName, $newIndexName = null)
         if ($oldIndex->isPrimary()) {
             $this->dropPrimaryKey();
 
-            return $this->setPrimaryKey($oldIndex->getColumns(), $newIndexName ?? false);
+            return $this->setPrimaryKey($oldIndex->getColumns(), $newIndexName ?? null);
         }
 
         unset($this->_indexes[$oldIndexName]);
@@ -271,11 +247,9 @@ public function renameIndex($oldIndexName, $newIndexName = null)
     /**
      * Checks if an index begins in the order of the given columns.
      *
-     * @param string[] $columnNames
-     *
-     * @return bool
+     * @param array<int, string> $columnNames
      */
-    public function columnsAreIndexed(array $columnNames)
+    public function columnsAreIndexed(array $columnNames) : bool
     {
         foreach ($this->getIndexes() as $index) {
             /** @var $index Index */
@@ -288,13 +262,9 @@ public function columnsAreIndexed(array $columnNames)
     }
 
     /**
-     * @param string  $columnName
-     * @param string  $typeName
-     * @param mixed[] $options
-     *
-     * @return Column
+     * @param array<string, mixed> $options
      */
-    public function addColumn($columnName, $typeName, array $options = [])
+    public function addColumn(string $columnName, string $typeName, array $options = []) : Column
     {
         $column = new Column($columnName, Type::getType($typeName), $options);
 
@@ -306,12 +276,9 @@ public function addColumn($columnName, $typeName, array $options = [])
     /**
      * Change Column Details.
      *
-     * @param string  $columnName
-     * @param mixed[] $options
-     *
-     * @return self
+     * @param array<string, mixed> $options
      */
-    public function changeColumn($columnName, array $options)
+    public function changeColumn(string $columnName, array $options) : self
     {
         $column = $this->getColumn($columnName);
 
@@ -322,12 +289,8 @@ public function changeColumn($columnName, array $options)
 
     /**
      * Drops a Column from the Table.
-     *
-     * @param string $columnName
-     *
-     * @return self
      */
-    public function dropColumn($columnName)
+    public function dropColumn(string $columnName) : self
     {
         $columnName = $this->normalizeIdentifier($columnName);
 
@@ -341,15 +304,12 @@ public function dropColumn($columnName)
      *
      * Name is inferred from the local columns.
      *
-     * @param Table|string $foreignTable       Table schema instance or table name
-     * @param string[]     $localColumnNames
-     * @param string[]     $foreignColumnNames
-     * @param mixed[]      $options
-     * @param string|null  $name
-     *
-     * @return self
+     * @param Table|string         $foreignTable       Table schema instance or table name
+     * @param array<int, string>   $localColumnNames
+     * @param array<int, string>   $foreignColumnNames
+     * @param array<string, mixed> $options
      */
-    public function addForeignKeyConstraint($foreignTable, array $localColumnNames, array $foreignColumnNames, array $options = [], $name = null)
+    public function addForeignKeyConstraint($foreignTable, array $localColumnNames, array $foreignColumnNames, array $options = [], ?string $name = null) : self
     {
         if (! $name) {
             $name = $this->_generateIdentifierName(
@@ -385,12 +345,9 @@ public function addForeignKeyConstraint($foreignTable, array $localColumnNames,
     }
 
     /**
-     * @param string $name
-     * @param mixed  $value
-     *
-     * @return self
+     * @param mixed $value
      */
-    public function addOption($name, $value)
+    public function addOption(string $name, $value) : self
     {
         $this->_options[$name] = $value;
 
@@ -399,12 +356,8 @@ public function addOption($name, $value)
 
     /**
      * Returns whether this table has a foreign key constraint with the given name.
-     *
-     * @param string $constraintName
-     *
-     * @return bool
      */
-    public function hasForeignKey($constraintName)
+    public function hasForeignKey(string $constraintName) : bool
     {
         $constraintName = $this->normalizeIdentifier($constraintName);
 
@@ -414,13 +367,9 @@ public function hasForeignKey($constraintName)
     /**
      * Returns the foreign key constraint with the given name.
      *
-     * @param string $constraintName The constraint name.
-     *
-     * @return ForeignKeyConstraint
-     *
      * @throws SchemaException If the foreign key does not exist.
      */
-    public function getForeignKey($constraintName)
+    public function getForeignKey(string $constraintName) : ForeignKeyConstraint
     {
         $constraintName = $this->normalizeIdentifier($constraintName);
 
@@ -434,13 +383,9 @@ public function getForeignKey($constraintName)
     /**
      * Removes the foreign key constraint with the given name.
      *
-     * @param string $constraintName The constraint name.
-     *
-     * @return void
-     *
      * @throws SchemaException
      */
-    public function removeForeignKey($constraintName)
+    public function removeForeignKey(string $constraintName) : void
     {
         $constraintName = $this->normalizeIdentifier($constraintName);
 
@@ -453,12 +398,8 @@ public function removeForeignKey($constraintName)
 
     /**
      * Returns whether this table has a unique constraint with the given name.
-     *
-     * @param string $constraintName
-     *
-     * @return bool
      */
-    public function hasUniqueConstraint($constraintName)
+    public function hasUniqueConstraint(string $constraintName) : bool
     {
         $constraintName = $this->normalizeIdentifier($constraintName);
 
@@ -468,13 +409,9 @@ public function hasUniqueConstraint($constraintName)
     /**
      * Returns the unique constraint with the given name.
      *
-     * @param string $constraintName The constraint name.
-     *
-     * @return UniqueConstraint
-     *
      * @throws SchemaException If the foreign key does not exist.
      */
-    public function getUniqueConstraint($constraintName)
+    public function getUniqueConstraint(string $constraintName) : UniqueConstraint
     {
         $constraintName = $this->normalizeIdentifier($constraintName);
 
@@ -488,13 +425,9 @@ public function getUniqueConstraint($constraintName)
     /**
      * Removes the unique constraint with the given name.
      *
-     * @param string $constraintName The constraint name.
-     *
-     * @return void
-     *
      * @throws SchemaException
      */
-    public function removeUniqueConstraint($constraintName)
+    public function removeUniqueConstraint(string $constraintName) : void
     {
         $constraintName = $this->normalizeIdentifier($constraintName);
 
@@ -508,9 +441,9 @@ public function removeUniqueConstraint($constraintName)
     /**
      * Returns ordered list of columns (primary keys are first, then foreign keys, then the rest)
      *
-     * @return Column[]
+     * @return array<string, Column>
      */
-    public function getColumns()
+    public function getColumns() : array
     {
         $columns = $this->_columns;
         $pkCols  = [];
@@ -538,12 +471,8 @@ public function getColumns()
 
     /**
      * Returns whether this table has a Column with the given name.
-     *
-     * @param string $columnName The column name.
-     *
-     * @return bool
      */
-    public function hasColumn($columnName)
+    public function hasColumn(string $columnName) : bool
     {
         $columnName = $this->normalizeIdentifier($columnName);
 
@@ -553,13 +482,9 @@ public function hasColumn($columnName)
     /**
      * Returns the Column with the given name.
      *
-     * @param string $columnName The column name.
-     *
-     * @return Column
-     *
      * @throws SchemaException If the column does not exist.
      */
-    public function getColumn($columnName)
+    public function getColumn(string $columnName) : Column
     {
         $columnName = $this->normalizeIdentifier($columnName);
 
@@ -572,10 +497,8 @@ public function getColumn($columnName)
 
     /**
      * Returns the primary key.
-     *
-     * @return Index|null The primary key, or null if this Table has no primary key.
      */
-    public function getPrimaryKey()
+    public function getPrimaryKey() : ?Index
     {
         return $this->hasPrimaryKey()
             ? $this->getIndex($this->_primaryKeyName)
@@ -585,11 +508,11 @@ public function getPrimaryKey()
     /**
      * Returns the primary key columns.
      *
-     * @return string[]
+     * @return array<int, string>
      *
      * @throws DBALException
      */
-    public function getPrimaryKeyColumns()
+    public function getPrimaryKeyColumns() : array
     {
         $primaryKey = $this->getPrimaryKey();
 
@@ -602,22 +525,16 @@ public function getPrimaryKeyColumns()
 
     /**
      * Returns whether this table has a primary key.
-     *
-     * @return bool
      */
-    public function hasPrimaryKey()
+    public function hasPrimaryKey() : bool
     {
         return $this->_primaryKeyName && $this->hasIndex($this->_primaryKeyName);
     }
 
     /**
      * Returns whether this table has an Index with the given name.
-     *
-     * @param string $indexName The index name.
-     *
-     * @return bool
      */
-    public function hasIndex($indexName)
+    public function hasIndex(string $indexName) : bool
     {
         $indexName = $this->normalizeIdentifier($indexName);
 
@@ -627,13 +544,9 @@ public function hasIndex($indexName)
     /**
      * Returns the Index with the given name.
      *
-     * @param string $indexName The index name.
-     *
-     * @return Index
-     *
      * @throws SchemaException If the index does not exist.
      */
-    public function getIndex($indexName)
+    public function getIndex(string $indexName) : Index
     {
         $indexName = $this->normalizeIdentifier($indexName);
 
@@ -645,9 +558,9 @@ public function getIndex($indexName)
     }
 
     /**
-     * @return Index[]
+     * @return array<string, Index>
      */
-    public function getIndexes()
+    public function getIndexes() : array
     {
         return $this->_indexes;
     }
@@ -655,9 +568,9 @@ public function getIndexes()
     /**
      * Returns the unique constraints.
      *
-     * @return UniqueConstraint[]
+     * @return array<string, UniqueConstraint>
      */
-    public function getUniqueConstraints()
+    public function getUniqueConstraints() : array
     {
         return $this->_uniqueConstraints;
     }
@@ -665,45 +578,35 @@ public function getUniqueConstraints()
     /**
      * Returns the foreign key constraints.
      *
-     * @return ForeignKeyConstraint[]
+     * @return array<string, ForeignKeyConstraint>
      */
     public function getForeignKeys()
     {
         return $this->_fkConstraints;
     }
 
-    /**
-     * @param string $name
-     *
-     * @return bool
-     */
-    public function hasOption($name)
+    public function hasOption(string $name) : bool
     {
         return isset($this->_options[$name]);
     }
 
     /**
-     * @param string $name
-     *
      * @return mixed
      */
-    public function getOption($name)
+    public function getOption(string $name)
     {
         return $this->_options[$name];
     }
 
     /**
-     * @return mixed[]
+     * @return array<string, mixed>
      */
-    public function getOptions()
+    public function getOptions() : array
     {
         return $this->_options;
     }
 
-    /**
-     * @return void
-     */
-    public function visit(Visitor $visitor)
+    public function visit(Visitor $visitor) : void
     {
         $visitor->acceptTable($this);
 
@@ -741,10 +644,7 @@ public function __clone()
         }
     }
 
-    /**
-     * @return int
-     */
-    protected function _getMaxIdentifierLength()
+    protected function _getMaxIdentifierLength() : int
     {
         return $this->_schemaConfig instanceof SchemaConfig
             ? $this->_schemaConfig->getMaxIdentifierLength()
@@ -752,11 +652,9 @@ protected function _getMaxIdentifierLength()
     }
 
     /**
-     * @return void
-     *
      * @throws SchemaException
      */
-    protected function _addColumn(Column $column)
+    protected function _addColumn(Column $column) : void
     {
         $columnName = $column->getName();
         $columnName = $this->normalizeIdentifier($columnName);
@@ -771,11 +669,9 @@ protected function _addColumn(Column $column)
     /**
      * Adds an index to the table.
      *
-     * @return self
-     *
      * @throws SchemaException
      */
-    protected function _addIndex(Index $indexCandidate)
+    protected function _addIndex(Index $indexCandidate) : self
     {
         $indexName               = $indexCandidate->getName();
         $indexName               = $this->normalizeIdentifier($indexName);
@@ -808,10 +704,7 @@ protected function _addIndex(Index $indexCandidate)
         return $this;
     }
 
-    /**
-     * @return self
-     */
-    protected function _addUniqueConstraint(UniqueConstraint $constraint)
+    protected function _addUniqueConstraint(UniqueConstraint $constraint) : self
     {
         $name = strlen($constraint->getName())
             ? $constraint->getName()
@@ -847,10 +740,7 @@ protected function _addUniqueConstraint(UniqueConstraint $constraint)
         return $this;
     }
 
-    /**
-     * @return self
-     */
-    protected function _addForeignKeyConstraint(ForeignKeyConstraint $constraint)
+    protected function _addForeignKeyConstraint(ForeignKeyConstraint $constraint) : self
     {
         $constraint->setLocalTable($this);
 
@@ -894,12 +784,8 @@ protected function _addForeignKeyConstraint(ForeignKeyConstraint $constraint)
      * Normalizes a given identifier.
      *
      * Trims quotes and lowercases the given identifier.
-     *
-     * @param string|null $identifier The identifier to normalize.
-     *
-     * @return string The normalized identifier.
      */
-    private function normalizeIdentifier($identifier)
+    private function normalizeIdentifier(?string $identifier) : string
     {
         if ($identifier === null) {
             return '';
@@ -922,16 +808,13 @@ public function getComment() : ?string
     }
 
     /**
-     * @param mixed[] $columns
-     * @param string  $indexName
-     * @param mixed[] $flags
-     * @param mixed[] $options
-     *
-     * @return UniqueConstraint
+     * @param array<string|int, string> $columns
+     * @param array<int, string>        $flags
+     * @param array<string, mixed>      $options
      *
      * @throws SchemaException
      */
-    private function _createUniqueConstraint(array $columns, $indexName, array $flags = [], array $options = [])
+    private function _createUniqueConstraint(array $columns, string $indexName, array $flags = [], array $options = []) : UniqueConstraint
     {
         if (preg_match('(([^a-zA-Z0-9_]+))', $this->normalizeIdentifier($indexName))) {
             throw IndexNameInvalid::new($indexName);
@@ -953,18 +836,13 @@ private function _createUniqueConstraint(array $columns, $indexName, array $flag
     }
 
     /**
-     * @param mixed[]  $columns
-     * @param string   $indexName
-     * @param bool     $isUnique
-     * @param bool     $isPrimary
-     * @param string[] $flags
-     * @param mixed[]  $options
-     *
-     * @return Index
+     * @param array<string|int, string> $columns
+     * @param array<int, string>        $flags
+     * @param array<string, mixed>      $options
      *
      * @throws SchemaException
      */
-    private function _createIndex(array $columns, $indexName, $isUnique, $isPrimary, array $flags = [], array $options = [])
+    private function _createIndex(array $columns, string $indexName, bool $isUnique, bool $isPrimary, array $flags = [], array $options = []) : Index
     {
         if (preg_match('(([^a-zA-Z0-9_]+))', $this->normalizeIdentifier($indexName))) {
             throw IndexNameInvalid::new($indexName);
diff --git a/lib/Doctrine/DBAL/Schema/TableDiff.php b/lib/Doctrine/DBAL/Schema/TableDiff.php
index bdbce7da3b3..0a8cf138a09 100644
--- a/lib/Doctrine/DBAL/Schema/TableDiff.php
+++ b/lib/Doctrine/DBAL/Schema/TableDiff.php
@@ -14,83 +14,83 @@ class TableDiff
     /** @var string */
     public $name = null;
 
-    /** @var string|false */
-    public $newName = false;
+    /** @var string|null */
+    public $newName = null;
 
     /**
      * All added fields.
      *
-     * @var Column[]
+     * @var array<string, Column>
      */
     public $addedColumns;
 
     /**
      * All changed fields.
      *
-     * @var ColumnDiff[]
+     * @var array<string, ColumnDiff>
      */
     public $changedColumns = [];
 
     /**
      * All removed fields.
      *
-     * @var Column[]
+     * @var array<string, Column>
      */
     public $removedColumns = [];
 
     /**
      * Columns that are only renamed from key to column instance name.
      *
-     * @var Column[]
+     * @var array<string, Column>
      */
     public $renamedColumns = [];
 
     /**
      * All added indexes.
      *
-     * @var Index[]
+     * @var array<string, Index>
      */
     public $addedIndexes = [];
 
     /**
      * All changed indexes.
      *
-     * @var Index[]
+     * @var array<string, Index>
      */
     public $changedIndexes = [];
 
     /**
      * All removed indexes
      *
-     * @var Index[]
+     * @var array<string, Index>
      */
     public $removedIndexes = [];
 
     /**
      * Indexes that are only renamed but are identical otherwise.
      *
-     * @var Index[]
+     * @var array<string, Index>
      */
     public $renamedIndexes = [];
 
     /**
      * All added foreign key definitions
      *
-     * @var ForeignKeyConstraint[]
+     * @var array<int, ForeignKeyConstraint>
      */
     public $addedForeignKeys = [];
 
     /**
      * All changed foreign keys
      *
-     * @var ForeignKeyConstraint[]
+     * @var array<int, ForeignKeyConstraint>
      */
     public $changedForeignKeys = [];
 
     /**
      * All removed foreign keys
      *
-     * @var ForeignKeyConstraint[]|string[]
+     * @var array<int, ForeignKeyConstraint>
      */
     public $removedForeignKeys = [];
 
@@ -100,22 +100,21 @@ class TableDiff
     /**
      * Constructs an TableDiff object.
      *
-     * @param string       $tableName
-     * @param Column[]     $addedColumns
-     * @param ColumnDiff[] $changedColumns
-     * @param Column[]     $removedColumns
-     * @param Index[]      $addedIndexes
-     * @param Index[]      $changedIndexes
-     * @param Index[]      $removedIndexes
+     * @param array<string, Column>     $addedColumns
+     * @param array<string, ColumnDiff> $changedColumns
+     * @param array<string, Column>     $removedColumns
+     * @param array<string, Index>      $addedIndexes
+     * @param array<string, Index>      $changedIndexes
+     * @param array<string, Index>      $removedIndexes
      */
     public function __construct(
-        $tableName,
-        $addedColumns = [],
-        $changedColumns = [],
-        $removedColumns = [],
-        $addedIndexes = [],
-        $changedIndexes = [],
-        $removedIndexes = [],
+        string $tableName,
+        array $addedColumns = [],
+        array $changedColumns = [],
+        array $removedColumns = [],
+        array $addedIndexes = [],
+        array $changedIndexes = [],
+        array $removedIndexes = [],
         ?Table $fromTable = null
     ) {
         $this->name           = $tableName;
@@ -130,23 +129,18 @@ public function __construct(
 
     /**
      * @param AbstractPlatform $platform The platform to use for retrieving this table diff's name.
-     *
-     * @return Identifier
      */
-    public function getName(AbstractPlatform $platform)
+    public function getName(AbstractPlatform $platform) : Identifier
     {
         return new Identifier(
             $this->fromTable instanceof Table ? $this->fromTable->getQuotedName($platform) : $this->name
         );
     }
 
-    /**
-     * @return Identifier|false
-     */
-    public function getNewName()
+    public function getNewName() : ?Identifier
     {
-        if ($this->newName === false) {
-            return false;
+        if ($this->newName === null) {
+            return null;
         }
 
         return new Identifier($this->newName);
diff --git a/lib/Doctrine/DBAL/Schema/UniqueConstraint.php b/lib/Doctrine/DBAL/Schema/UniqueConstraint.php
index 2ffe6022ab5..75d6f76b391 100644
--- a/lib/Doctrine/DBAL/Schema/UniqueConstraint.php
+++ b/lib/Doctrine/DBAL/Schema/UniqueConstraint.php
@@ -16,34 +16,31 @@ class UniqueConstraint extends AbstractAsset implements Constraint
 {
     /**
      * Asset identifier instances of the column names the unique constraint is associated with.
-     * array($columnName => Identifier)
      *
-     * @var Identifier[]
+     * @var array<string, Identifier>
      */
     protected $columns = [];
 
     /**
      * Platform specific flags
-     * array($flagName => true)
      *
-     * @var true[]
+     * @var array<string, true>
      */
     protected $flags = [];
 
     /**
      * Platform specific options
      *
-     * @var mixed[]
+     * @var array<string, mixed>
      */
     private $options = [];
 
     /**
-     * @param string   $indexName
-     * @param string[] $columns
-     * @param string[] $flags
-     * @param mixed[]  $options
+     * @param array<string>        $columns
+     * @param array<string>        $flags
+     * @param array<string, mixed> $options
      */
-    public function __construct($indexName, array $columns, array $flags = [], array $options = [])
+    public function __construct(string $indexName, array $columns, array $flags = [], array $options = [])
     {
         $this->_setName($indexName);
 
@@ -61,7 +58,7 @@ public function __construct($indexName, array $columns, array $flags = [], array
     /**
      * {@inheritdoc}
      */
-    public function getColumns()
+    public function getColumns() : array
     {
         return array_keys($this->columns);
     }
@@ -69,7 +66,7 @@ public function getColumns()
     /**
      * {@inheritdoc}
      */
-    public function getQuotedColumns(AbstractPlatform $platform)
+    public function getQuotedColumns(AbstractPlatform $platform) : array
     {
         $columns = [];
 
@@ -81,9 +78,9 @@ public function getQuotedColumns(AbstractPlatform $platform)
     }
 
     /**
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getUnquotedColumns()
+    public function getUnquotedColumns() : array
     {
         return array_map([$this, 'trimQuotes'], $this->getColumns());
     }
@@ -91,9 +88,9 @@ public function getUnquotedColumns()
     /**
      * Returns platform specific flags for unique constraint.
      *
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getFlags()
+    public function getFlags() : array
     {
         return array_keys($this->flags);
     }
@@ -101,13 +98,9 @@ public function getFlags()
     /**
      * Adds flag for a unique constraint that translates to platform specific handling.
      *
-     * @param string $flag
-     *
-     * @return self
-     *
      * @example $uniqueConstraint->addFlag('CLUSTERED')
      */
-    public function addFlag($flag)
+    public function addFlag(string $flag) : self
     {
         $this->flags[strtolower($flag)] = true;
 
@@ -116,52 +109,37 @@ public function addFlag($flag)
 
     /**
      * Does this unique constraint have a specific flag?
-     *
-     * @param string $flag
-     *
-     * @return bool
      */
-    public function hasFlag($flag)
+    public function hasFlag(string $flag) : bool
     {
         return isset($this->flags[strtolower($flag)]);
     }
 
     /**
      * Removes a flag.
-     *
-     * @param string $flag
-     *
-     * @return void
      */
-    public function removeFlag($flag)
+    public function removeFlag(string $flag) : void
     {
         unset($this->flags[strtolower($flag)]);
     }
 
-    /**
-     * @param string $name
-     *
-     * @return bool
-     */
-    public function hasOption($name)
+    public function hasOption(string $name) : bool
     {
         return isset($this->options[strtolower($name)]);
     }
 
     /**
-     * @param string $name
-     *
      * @return mixed
      */
-    public function getOption($name)
+    public function getOption(string $name)
     {
         return $this->options[strtolower($name)];
     }
 
     /**
-     * @return mixed[]
+     * @return array<string, mixed>
      */
-    public function getOptions()
+    public function getOptions() : array
     {
         return $this->options;
     }
diff --git a/lib/Doctrine/DBAL/Schema/View.php b/lib/Doctrine/DBAL/Schema/View.php
index 18ca8664c9e..f67b203036e 100644
--- a/lib/Doctrine/DBAL/Schema/View.php
+++ b/lib/Doctrine/DBAL/Schema/View.php
@@ -12,20 +12,13 @@ class View extends AbstractAsset
     /** @var string */
     private $sql;
 
-    /**
-     * @param string $name
-     * @param string $sql
-     */
-    public function __construct($name, $sql)
+    public function __construct(string $name, string $sql)
     {
         $this->_setName($name);
         $this->sql = $sql;
     }
 
-    /**
-     * @return string
-     */
-    public function getSql()
+    public function getSql() : string
     {
         return $this->sql;
     }
diff --git a/lib/Doctrine/DBAL/Schema/Visitor/AbstractVisitor.php b/lib/Doctrine/DBAL/Schema/Visitor/AbstractVisitor.php
index 318ba1f1126..bb3abff57f9 100644
--- a/lib/Doctrine/DBAL/Schema/Visitor/AbstractVisitor.php
+++ b/lib/Doctrine/DBAL/Schema/Visitor/AbstractVisitor.php
@@ -16,34 +16,34 @@
  */
 class AbstractVisitor implements Visitor, NamespaceVisitor
 {
-    public function acceptSchema(Schema $schema)
+    public function acceptSchema(Schema $schema) : void
     {
     }
 
     /**
      * {@inheritdoc}
      */
-    public function acceptNamespace($namespaceName)
+    public function acceptNamespace(string $namespaceName) : void
     {
     }
 
-    public function acceptTable(Table $table)
+    public function acceptTable(Table $table) : void
     {
     }
 
-    public function acceptColumn(Table $table, Column $column)
+    public function acceptColumn(Table $table, Column $column) : void
     {
     }
 
-    public function acceptForeignKey(Table $localTable, ForeignKeyConstraint $fkConstraint)
+    public function acceptForeignKey(Table $localTable, ForeignKeyConstraint $fkConstraint) : void
     {
     }
 
-    public function acceptIndex(Table $table, Index $index)
+    public function acceptIndex(Table $table, Index $index) : void
     {
     }
 
-    public function acceptSequence(Sequence $sequence)
+    public function acceptSequence(Sequence $sequence) : void
     {
     }
 }
diff --git a/lib/Doctrine/DBAL/Schema/Visitor/CreateSchemaSqlCollector.php b/lib/Doctrine/DBAL/Schema/Visitor/CreateSchemaSqlCollector.php
index cea93eeb4f1..ccba4688c95 100644
--- a/lib/Doctrine/DBAL/Schema/Visitor/CreateSchemaSqlCollector.php
+++ b/lib/Doctrine/DBAL/Schema/Visitor/CreateSchemaSqlCollector.php
@@ -12,16 +12,16 @@
 
 class CreateSchemaSqlCollector extends AbstractVisitor
 {
-    /** @var string[] */
+    /** @var array<string> */
     private $createNamespaceQueries = [];
 
-    /** @var string[] */
+    /** @var array<string> */
     private $createTableQueries = [];
 
-    /** @var string[] */
+    /** @var array<string> */
     private $createSequenceQueries = [];
 
-    /** @var string[] */
+    /** @var array<string> */
     private $createFkConstraintQueries = [];
 
     /** @var AbstractPlatform */
@@ -35,7 +35,7 @@ public function __construct(AbstractPlatform $platform)
     /**
      * {@inheritdoc}
      */
-    public function acceptNamespace($namespaceName)
+    public function acceptNamespace(string $namespaceName) : void
     {
         if (! $this->platform->supportsSchemas()) {
             return;
@@ -47,7 +47,7 @@ public function acceptNamespace($namespaceName)
     /**
      * {@inheritdoc}
      */
-    public function acceptTable(Table $table)
+    public function acceptTable(Table $table) : void
     {
         $this->createTableQueries = array_merge($this->createTableQueries, $this->platform->getCreateTableSQL($table));
     }
@@ -55,7 +55,7 @@ public function acceptTable(Table $table)
     /**
      * {@inheritdoc}
      */
-    public function acceptForeignKey(Table $localTable, ForeignKeyConstraint $fkConstraint)
+    public function acceptForeignKey(Table $localTable, ForeignKeyConstraint $fkConstraint) : void
     {
         if (! $this->platform->supportsForeignKeyConstraints()) {
             return;
@@ -67,15 +67,12 @@ public function acceptForeignKey(Table $localTable, ForeignKeyConstraint $fkCons
     /**
      * {@inheritdoc}
      */
-    public function acceptSequence(Sequence $sequence)
+    public function acceptSequence(Sequence $sequence) : void
     {
         $this->createSequenceQueries[] = $this->platform->getCreateSequenceSQL($sequence);
     }
 
-    /**
-     * @return void
-     */
-    public function resetQueries()
+    public function resetQueries() : void
     {
         $this->createNamespaceQueries    = [];
         $this->createTableQueries        = [];
@@ -86,9 +83,9 @@ public function resetQueries()
     /**
      * Gets all queries collected so far.
      *
-     * @return string[]
+     * @return array<string>
      */
-    public function getQueries()
+    public function getQueries() : array
     {
         return array_merge(
             $this->createNamespaceQueries,
diff --git a/lib/Doctrine/DBAL/Schema/Visitor/DropSchemaSqlCollector.php b/lib/Doctrine/DBAL/Schema/Visitor/DropSchemaSqlCollector.php
index 59d8e04a851..f51b547a44a 100644
--- a/lib/Doctrine/DBAL/Schema/Visitor/DropSchemaSqlCollector.php
+++ b/lib/Doctrine/DBAL/Schema/Visitor/DropSchemaSqlCollector.php
@@ -38,7 +38,7 @@ public function __construct(AbstractPlatform $platform)
     /**
      * {@inheritdoc}
      */
-    public function acceptTable(Table $table)
+    public function acceptTable(Table $table) : void
     {
         $this->tables->attach($table);
     }
@@ -46,7 +46,7 @@ public function acceptTable(Table $table)
     /**
      * {@inheritdoc}
      */
-    public function acceptForeignKey(Table $localTable, ForeignKeyConstraint $fkConstraint)
+    public function acceptForeignKey(Table $localTable, ForeignKeyConstraint $fkConstraint) : void
     {
         if (strlen($fkConstraint->getName()) === 0) {
             throw NamedForeignKeyRequired::new($localTable, $fkConstraint);
@@ -58,15 +58,12 @@ public function acceptForeignKey(Table $localTable, ForeignKeyConstraint $fkCons
     /**
      * {@inheritdoc}
      */
-    public function acceptSequence(Sequence $sequence)
+    public function acceptSequence(Sequence $sequence) : void
     {
         $this->sequences->attach($sequence);
     }
 
-    /**
-     * @return void
-     */
-    public function clearQueries()
+    public function clearQueries() : void
     {
         $this->constraints = new SplObjectStorage();
         $this->sequences   = new SplObjectStorage();
@@ -74,9 +71,9 @@ public function clearQueries()
     }
 
     /**
-     * @return string[]
+     * @return array<int, string>
      */
-    public function getQueries()
+    public function getQueries() : array
     {
         $sql = [];
 
diff --git a/lib/Doctrine/DBAL/Schema/Visitor/Graphviz.php b/lib/Doctrine/DBAL/Schema/Visitor/Graphviz.php
index 96aa180133a..3f81b5c217c 100644
--- a/lib/Doctrine/DBAL/Schema/Visitor/Graphviz.php
+++ b/lib/Doctrine/DBAL/Schema/Visitor/Graphviz.php
@@ -23,7 +23,7 @@ class Graphviz extends AbstractVisitor
     /**
      * {@inheritdoc}
      */
-    public function acceptForeignKey(Table $localTable, ForeignKeyConstraint $fkConstraint)
+    public function acceptForeignKey(Table $localTable, ForeignKeyConstraint $fkConstraint) : void
     {
         $this->output .= $this->createNodeRelation(
             $fkConstraint->getLocalTableName() . ':col' . current($fkConstraint->getLocalColumns()) . ':se',
@@ -39,7 +39,7 @@ public function acceptForeignKey(Table $localTable, ForeignKeyConstraint $fkCons
     /**
      * {@inheritdoc}
      */
-    public function acceptSchema(Schema $schema)
+    public function acceptSchema(Schema $schema) : void
     {
         $this->output  = 'digraph "' . $schema->getName() . '" {' . "\n";
         $this->output .= 'splines = true;' . "\n";
@@ -52,7 +52,7 @@ public function acceptSchema(Schema $schema)
     /**
      * {@inheritdoc}
      */
-    public function acceptTable(Table $table)
+    public function acceptTable(Table $table) : void
     {
         $this->output .= $this->createNode(
             $table->getName(),
@@ -63,10 +63,7 @@ public function acceptTable(Table $table)
         );
     }
 
-    /**
-     * @return string
-     */
-    private function createTableLabel(Table $table)
+    private function createTableLabel(Table $table) : string
     {
         // Start the table
         $label = '<<TABLE CELLSPACING="0" BORDER="1" ALIGN="LEFT">';
@@ -99,12 +96,9 @@ private function createTableLabel(Table $table)
     }
 
     /**
-     * @param string   $name
-     * @param string[] $options
-     *
-     * @return string
+     * @param array<string, string> $options
      */
-    private function createNode($name, $options)
+    private function createNode(string $name, array $options) : string
     {
         $node = $name . ' [';
         foreach ($options as $key => $value) {
@@ -116,13 +110,9 @@ private function createNode($name, $options)
     }
 
     /**
-     * @param string   $node1
-     * @param string   $node2
-     * @param string[] $options
-     *
-     * @return string
+     * @param array<string, string> $options
      */
-    private function createNodeRelation($node1, $node2, $options)
+    private function createNodeRelation(string $node1, string $node2, array $options) : string
     {
         $relation = $node1 . ' -> ' . $node2 . ' [';
         foreach ($options as $key => $value) {
@@ -135,10 +125,8 @@ private function createNodeRelation($node1, $node2, $options)
 
     /**
      * Get Graphviz Output
-     *
-     * @return string
      */
-    public function getOutput()
+    public function getOutput() : string
     {
         return $this->output . '}';
     }
@@ -150,12 +138,8 @@ public function getOutput()
      * and execute:
      *
      *  neato -Tpng -o er.png er.dot
-     *
-     * @param string $filename
-     *
-     * @return void
      */
-    public function write($filename)
+    public function write(string $filename) : void
     {
         file_put_contents($filename, $this->getOutput());
     }
diff --git a/lib/Doctrine/DBAL/Schema/Visitor/NamespaceVisitor.php b/lib/Doctrine/DBAL/Schema/Visitor/NamespaceVisitor.php
index fd09ff7cdab..90e10b91b70 100644
--- a/lib/Doctrine/DBAL/Schema/Visitor/NamespaceVisitor.php
+++ b/lib/Doctrine/DBAL/Schema/Visitor/NamespaceVisitor.php
@@ -14,5 +14,5 @@ interface NamespaceVisitor
      *
      * @param string $namespaceName The schema namespace name to accept.
      */
-    public function acceptNamespace($namespaceName);
+    public function acceptNamespace(string $namespaceName) : void;
 }
diff --git a/lib/Doctrine/DBAL/Schema/Visitor/RemoveNamespacedAssets.php b/lib/Doctrine/DBAL/Schema/Visitor/RemoveNamespacedAssets.php
index 196e43e46c3..78991298872 100644
--- a/lib/Doctrine/DBAL/Schema/Visitor/RemoveNamespacedAssets.php
+++ b/lib/Doctrine/DBAL/Schema/Visitor/RemoveNamespacedAssets.php
@@ -28,7 +28,7 @@ class RemoveNamespacedAssets extends AbstractVisitor
     /**
      * {@inheritdoc}
      */
-    public function acceptSchema(Schema $schema)
+    public function acceptSchema(Schema $schema) : void
     {
         $this->schema = $schema;
     }
@@ -36,7 +36,7 @@ public function acceptSchema(Schema $schema)
     /**
      * {@inheritdoc}
      */
-    public function acceptTable(Table $table)
+    public function acceptTable(Table $table) : void
     {
         if ($table->isInDefaultNamespace($this->schema->getName())) {
             return;
@@ -48,7 +48,7 @@ public function acceptTable(Table $table)
     /**
      * {@inheritdoc}
      */
-    public function acceptSequence(Sequence $sequence)
+    public function acceptSequence(Sequence $sequence) : void
     {
         if ($sequence->isInDefaultNamespace($this->schema->getName())) {
             return;
@@ -60,7 +60,7 @@ public function acceptSequence(Sequence $sequence)
     /**
      * {@inheritdoc}
      */
-    public function acceptForeignKey(Table $localTable, ForeignKeyConstraint $fkConstraint)
+    public function acceptForeignKey(Table $localTable, ForeignKeyConstraint $fkConstraint) : void
     {
         // The table may already be deleted in a previous
         // RemoveNamespacedAssets#acceptTable call. Removing Foreign keys that
diff --git a/lib/Doctrine/DBAL/Schema/Visitor/Visitor.php b/lib/Doctrine/DBAL/Schema/Visitor/Visitor.php
index 3d80991c4d9..071f0ebf177 100644
--- a/lib/Doctrine/DBAL/Schema/Visitor/Visitor.php
+++ b/lib/Doctrine/DBAL/Schema/Visitor/Visitor.php
@@ -16,33 +16,15 @@
  */
 interface Visitor
 {
-    /**
-     * @return void
-     */
-    public function acceptSchema(Schema $schema);
-
-    /**
-     * @return void
-     */
-    public function acceptTable(Table $table);
-
-    /**
-     * @return void
-     */
-    public function acceptColumn(Table $table, Column $column);
-
-    /**
-     * @return void
-     */
-    public function acceptForeignKey(Table $localTable, ForeignKeyConstraint $fkConstraint);
-
-    /**
-     * @return void
-     */
-    public function acceptIndex(Table $table, Index $index);
-
-    /**
-     * @return void
-     */
-    public function acceptSequence(Sequence $sequence);
+    public function acceptSchema(Schema $schema) : void;
+
+    public function acceptTable(Table $table) : void;
+
+    public function acceptColumn(Table $table, Column $column) : void;
+
+    public function acceptForeignKey(Table $localTable, ForeignKeyConstraint $fkConstraint) : void;
+
+    public function acceptIndex(Table $table, Index $index) : void;
+
+    public function acceptSequence(Sequence $sequence) : void;
 }
diff --git a/lib/Doctrine/DBAL/Sharding/SQLAzure/SQLAzureFederationsSynchronizer.php b/lib/Doctrine/DBAL/Sharding/SQLAzure/SQLAzureFederationsSynchronizer.php
index d7501b27897..c372f416fca 100644
--- a/lib/Doctrine/DBAL/Sharding/SQLAzure/SQLAzureFederationsSynchronizer.php
+++ b/lib/Doctrine/DBAL/Sharding/SQLAzure/SQLAzureFederationsSynchronizer.php
@@ -44,7 +44,7 @@ public function __construct(Connection $conn, SQLAzureShardManager $shardManager
     /**
      * {@inheritdoc}
      */
-    public function getCreateSchema(Schema $createSchema)
+    public function getCreateSchema(Schema $createSchema) : array
     {
         $sql = [];
 
@@ -73,7 +73,7 @@ public function getCreateSchema(Schema $createSchema)
     /**
      * {@inheritdoc}
      */
-    public function getUpdateSchema(Schema $toSchema, $noDrops = false)
+    public function getUpdateSchema(Schema $toSchema, bool $noDrops = false) : array
     {
         return $this->work($toSchema, static function ($synchronizer, $schema) use ($noDrops) {
             return $synchronizer->getUpdateSchema($schema, $noDrops);
@@ -83,7 +83,7 @@ public function getUpdateSchema(Schema $toSchema, $noDrops = false)
     /**
      * {@inheritdoc}
      */
-    public function getDropSchema(Schema $dropSchema)
+    public function getDropSchema(Schema $dropSchema) : array
     {
         return $this->work($dropSchema, static function ($synchronizer, $schema) {
             return $synchronizer->getDropSchema($schema);
@@ -93,7 +93,7 @@ public function getDropSchema(Schema $dropSchema)
     /**
      * {@inheritdoc}
      */
-    public function createSchema(Schema $createSchema)
+    public function createSchema(Schema $createSchema) : void
     {
         $this->processSql($this->getCreateSchema($createSchema));
     }
@@ -101,7 +101,7 @@ public function createSchema(Schema $createSchema)
     /**
      * {@inheritdoc}
      */
-    public function updateSchema(Schema $toSchema, $noDrops = false)
+    public function updateSchema(Schema $toSchema, bool $noDrops = false) : void
     {
         $this->processSql($this->getUpdateSchema($toSchema, $noDrops));
     }
@@ -109,7 +109,7 @@ public function updateSchema(Schema $toSchema, $noDrops = false)
     /**
      * {@inheritdoc}
      */
-    public function dropSchema(Schema $dropSchema)
+    public function dropSchema(Schema $dropSchema) : void
     {
         $this->processSqlSafely($this->getDropSchema($dropSchema));
     }
@@ -117,7 +117,7 @@ public function dropSchema(Schema $dropSchema)
     /**
      * {@inheritdoc}
      */
-    public function getDropAllSchema()
+    public function getDropAllSchema() : array
     {
         $this->shardManager->selectGlobal();
         $globalSql = $this->synchronizer->getDropAllSchema();
@@ -150,7 +150,7 @@ public function getDropAllSchema()
     /**
      * {@inheritdoc}
      */
-    public function dropAllSchema()
+    public function dropAllSchema() : void
     {
         $this->processSqlSafely($this->getDropAllSchema());
     }
diff --git a/lib/Doctrine/DBAL/Sharding/SQLAzure/Schema/MultiTenantVisitor.php b/lib/Doctrine/DBAL/Sharding/SQLAzure/Schema/MultiTenantVisitor.php
index 21f3762ba0c..da5328aed8f 100644
--- a/lib/Doctrine/DBAL/Sharding/SQLAzure/Schema/MultiTenantVisitor.php
+++ b/lib/Doctrine/DBAL/Sharding/SQLAzure/Schema/MultiTenantVisitor.php
@@ -68,7 +68,7 @@ public function __construct(array $excludedTables = [], $tenantColumnName = 'ten
     /**
      * {@inheritdoc}
      */
-    public function acceptTable(Table $table)
+    public function acceptTable(Table $table) : void
     {
         if (in_array($table->getName(), $this->excludedTables)) {
             return;
@@ -117,35 +117,35 @@ private function getClusteredIndex($table)
     /**
      * {@inheritdoc}
      */
-    public function acceptSchema(Schema $schema)
+    public function acceptSchema(Schema $schema) : void
     {
     }
 
     /**
      * {@inheritdoc}
      */
-    public function acceptColumn(Table $table, Column $column)
+    public function acceptColumn(Table $table, Column $column) : void
     {
     }
 
     /**
      * {@inheritdoc}
      */
-    public function acceptForeignKey(Table $localTable, ForeignKeyConstraint $fkConstraint)
+    public function acceptForeignKey(Table $localTable, ForeignKeyConstraint $fkConstraint) : void
     {
     }
 
     /**
      * {@inheritdoc}
      */
-    public function acceptIndex(Table $table, Index $index)
+    public function acceptIndex(Table $table, Index $index) : void
     {
     }
 
     /**
      * {@inheritdoc}
      */
-    public function acceptSequence(Sequence $sequence)
+    public function acceptSequence(Sequence $sequence) : void
     {
     }
 }
diff --git a/tests/Doctrine/Tests/DBAL/Functional/Driver/PDOSqlite/DriverTest.php b/tests/Doctrine/Tests/DBAL/Functional/Driver/PDOSqlite/DriverTest.php
index a7a6fe6e36d..73f15abdf5e 100644
--- a/tests/Doctrine/Tests/DBAL/Functional/Driver/PDOSqlite/DriverTest.php
+++ b/tests/Doctrine/Tests/DBAL/Functional/Driver/PDOSqlite/DriverTest.php
@@ -41,4 +41,9 @@ protected function createDriver() : DriverInterface
     {
         return new Driver();
     }
+
+    protected static function getDatabaseNameForConnectionWithoutDatabaseNameParameter() : ?string
+    {
+        return '';
+    }
 }
diff --git a/tests/Doctrine/Tests/DBAL/Functional/NamedParametersTest.php b/tests/Doctrine/Tests/DBAL/Functional/NamedParametersTest.php
index 5b11125fda7..31591417d1c 100644
--- a/tests/Doctrine/Tests/DBAL/Functional/NamedParametersTest.php
+++ b/tests/Doctrine/Tests/DBAL/Functional/NamedParametersTest.php
@@ -156,7 +156,7 @@ protected function setUp() : void
     {
         parent::setUp();
 
-        if ($this->connection->getSchemaManager()->tablesExist('ddc1372_foobar')) {
+        if ($this->connection->getSchemaManager()->tableExists('ddc1372_foobar')) {
             return;
         }
 
diff --git a/tests/Doctrine/Tests/DBAL/Functional/Schema/ComparatorTest.php b/tests/Doctrine/Tests/DBAL/Functional/Schema/ComparatorTest.php
index 13503e3187b..ad8fd6ed92a 100644
--- a/tests/Doctrine/Tests/DBAL/Functional/Schema/ComparatorTest.php
+++ b/tests/Doctrine/Tests/DBAL/Functional/Schema/ComparatorTest.php
@@ -39,7 +39,7 @@ public function testDefaultValueComparison(string $type, $value) : void
 
         $onlineTable = $this->schemaManager->listTableDetails('default_value');
 
-        self::assertFalse($this->comparator->diffTable($table, $onlineTable));
+        self::assertNull($this->comparator->diffTable($table, $onlineTable));
     }
 
     /**
diff --git a/tests/Doctrine/Tests/DBAL/Functional/Schema/MySqlSchemaManagerTest.php b/tests/Doctrine/Tests/DBAL/Functional/Schema/MySqlSchemaManagerTest.php
index 93017676f31..179f64408a7 100644
--- a/tests/Doctrine/Tests/DBAL/Functional/Schema/MySqlSchemaManagerTest.php
+++ b/tests/Doctrine/Tests/DBAL/Functional/Schema/MySqlSchemaManagerTest.php
@@ -5,6 +5,8 @@
 namespace Doctrine\Tests\DBAL\Functional\Schema;
 
 use DateTime;
+use Doctrine\DBAL\DriverManager;
+use Doctrine\DBAL\Exception\DatabaseRequired;
 use Doctrine\DBAL\Platforms\MariaDb1027Platform;
 use Doctrine\DBAL\Platforms\MySqlPlatform;
 use Doctrine\DBAL\Schema\Comparator;
@@ -12,6 +14,7 @@
 use Doctrine\DBAL\Schema\Table;
 use Doctrine\DBAL\Types\Type;
 use Doctrine\DBAL\Types\Types;
+use Doctrine\Tests\TestUtil;
 use Doctrine\Tests\Types\MySqlPointType;
 
 class MySqlSchemaManagerTest extends SchemaManagerFunctionalTestCase
@@ -71,7 +74,7 @@ public function testDiffTableBug() : void
         $comparator = new Comparator();
         $diff       = $comparator->diffTable($tableFetched, $table);
 
-        self::assertFalse($diff, 'no changes expected.');
+        self::assertNull($diff, 'no changes expected.');
     }
 
     public function testFulltextIndex() : void
@@ -360,7 +363,7 @@ public function testDiffListGuidTableColumn() : void
 
         $comparator = new Comparator();
 
-        self::assertFalse(
+        self::assertNull(
             $comparator->diffTable($offlineTable, $onlineTable),
             'No differences should be detected with the offline vs online schema.'
         );
@@ -439,7 +442,7 @@ public function testColumnDefaultCurrentTimestamp() : void
         $comparator = new Comparator();
 
         $diff = $comparator->diffTable($table, $onlineTable);
-        self::assertFalse($diff, 'Tables should be identical with column defaults.');
+        self::assertNull($diff, 'Tables should be identical with column defaults.');
     }
 
     public function testColumnDefaultsAreValid() : void
@@ -514,7 +517,7 @@ public function testColumnDefaultValuesCurrentTimeAndDate() : void
         $comparator = new Comparator();
 
         $diff = $comparator->diffTable($table, $onlineTable);
-        self::assertFalse($diff, 'Tables should be identical with column defauts time and date.');
+        self::assertNull($diff, 'Tables should be identical with column defauts time and date.');
     }
 
     public function testEnsureTableOptionsAreReflectedInMetadata() : void
@@ -566,4 +569,18 @@ public function testParseNullCreateOptions() : void
 
         self::assertEquals([], $table->getOption('create_options'));
     }
+
+    public function testListTableColumnsThrowsDatabaseRequired() : void
+    {
+        $params = TestUtil::getConnectionParams();
+        unset($params['dbname']);
+
+        $connection    = DriverManager::getConnection($params);
+        $schemaManager = $connection->getSchemaManager();
+
+        self::expectException(DatabaseRequired::class);
+        self::expectExceptionMessage('A database is required for the method: Doctrine\DBAL\Schema\AbstractSchemaManager::listTableColumns');
+
+        $schemaManager->listTableColumns('users');
+    }
 }
diff --git a/tests/Doctrine/Tests/DBAL/Functional/Schema/PostgreSqlSchemaManagerTest.php b/tests/Doctrine/Tests/DBAL/Functional/Schema/PostgreSqlSchemaManagerTest.php
index cae1835500b..b70eedf5a64 100644
--- a/tests/Doctrine/Tests/DBAL/Functional/Schema/PostgreSqlSchemaManagerTest.php
+++ b/tests/Doctrine/Tests/DBAL/Functional/Schema/PostgreSqlSchemaManagerTest.php
@@ -300,7 +300,7 @@ public function testBooleanDefault() : void
         $c    = new Comparator();
         $diff = $c->diffTable($table, $databaseTable);
 
-        self::assertFalse($diff);
+        self::assertNull($diff);
     }
 
     public function testListTableWithBinary() : void
@@ -339,7 +339,7 @@ public function testListQuotedTable() : void
 
         $comparator = new Schema\Comparator();
 
-        self::assertFalse($comparator->diffTable($offlineTable, $onlineTable));
+        self::assertNull($comparator->diffTable($offlineTable, $onlineTable));
     }
 
     public function testListTablesExcludesViews() : void
@@ -385,7 +385,7 @@ public function testPartialIndexes() : void
 
         $comparator = new Schema\Comparator();
 
-        self::assertFalse($comparator->diffTable($offlineTable, $onlineTable));
+        self::assertNull($comparator->diffTable($offlineTable, $onlineTable));
         self::assertTrue($onlineTable->hasIndex('simple_partial_index'));
         self::assertTrue($onlineTable->getIndex('simple_partial_index')->hasOption('where'));
         self::assertSame('(id IS NULL)', $onlineTable->getIndex('simple_partial_index')->getOption('where'));
diff --git a/tests/Doctrine/Tests/DBAL/Functional/Schema/SchemaManagerFunctionalTestCase.php b/tests/Doctrine/Tests/DBAL/Functional/Schema/SchemaManagerFunctionalTestCase.php
index 3753a8e779e..9424120f329 100644
--- a/tests/Doctrine/Tests/DBAL/Functional/Schema/SchemaManagerFunctionalTestCase.php
+++ b/tests/Doctrine/Tests/DBAL/Functional/Schema/SchemaManagerFunctionalTestCase.php
@@ -430,7 +430,7 @@ public function testDiffListTableColumns() : void
         $comparator = new Comparator();
         $diff       = $comparator->diffTable($offlineTable, $onlineTable);
 
-        self::assertFalse($diff, 'No differences should be detected with the offline vs online schema.');
+        self::assertNull($diff, 'No differences should be detected with the offline vs online schema.');
     }
 
     public function testListTableIndexes() : void
@@ -1317,7 +1317,7 @@ public function testComparatorShouldNotAddCommentToJsonTypeSinceItIsTheDefaultNo
         $comparator = new Comparator();
         $tableDiff  = $comparator->diffTable($this->schemaManager->listTableDetails('json_test'), $table);
 
-        self::assertFalse($tableDiff);
+        self::assertNull($tableDiff);
     }
 
     /**
diff --git a/tests/Doctrine/Tests/DBAL/Functional/Schema/SqliteSchemaManagerTest.php b/tests/Doctrine/Tests/DBAL/Functional/Schema/SqliteSchemaManagerTest.php
index 404b3ac0ad1..7a0441e5b5d 100644
--- a/tests/Doctrine/Tests/DBAL/Functional/Schema/SqliteSchemaManagerTest.php
+++ b/tests/Doctrine/Tests/DBAL/Functional/Schema/SqliteSchemaManagerTest.php
@@ -237,7 +237,7 @@ public function testDiffListIntegerAutoincrementTableColumns(string $integerType
         if ($expectedComparatorDiff) {
             self::assertEmpty($this->schemaManager->getDatabasePlatform()->getAlterTableSQL($diff));
         } else {
-            self::assertFalse($diff);
+            self::assertNull($diff);
         }
     }
 
diff --git a/tests/Doctrine/Tests/DBAL/Functional/Ticket/DBAL202Test.php b/tests/Doctrine/Tests/DBAL/Functional/Ticket/DBAL202Test.php
index fd049e01901..82ea59db185 100644
--- a/tests/Doctrine/Tests/DBAL/Functional/Ticket/DBAL202Test.php
+++ b/tests/Doctrine/Tests/DBAL/Functional/Ticket/DBAL202Test.php
@@ -20,7 +20,7 @@ protected function setUp() : void
             $this->markTestSkipped('OCI8 only test');
         }
 
-        if ($this->connection->getSchemaManager()->tablesExist('DBAL202')) {
+        if ($this->connection->getSchemaManager()->tableExists('DBAL202')) {
             $this->connection->exec('DELETE FROM DBAL202');
         } else {
             $table = new Table('DBAL202');
diff --git a/tests/Doctrine/Tests/DBAL/Functional/Ticket/DBAL510Test.php b/tests/Doctrine/Tests/DBAL/Functional/Ticket/DBAL510Test.php
index 989e1a77e21..37b7ae5cfb0 100644
--- a/tests/Doctrine/Tests/DBAL/Functional/Ticket/DBAL510Test.php
+++ b/tests/Doctrine/Tests/DBAL/Functional/Ticket/DBAL510Test.php
@@ -37,6 +37,6 @@ public function testSearchPathSchemaChanges() : void
         $comparator = new Comparator();
         $diff       = $comparator->diffTable($onlineTable, $table);
 
-        self::assertFalse($diff);
+        self::assertNull($diff);
     }
 }
diff --git a/tests/Doctrine/Tests/DBAL/Schema/ComparatorTest.php b/tests/Doctrine/Tests/DBAL/Schema/ComparatorTest.php
index 9dde0c9d4fc..56807ab78ae 100644
--- a/tests/Doctrine/Tests/DBAL/Schema/ComparatorTest.php
+++ b/tests/Doctrine/Tests/DBAL/Schema/ComparatorTest.php
@@ -484,13 +484,11 @@ public function testCompareSequences() : void
         $seq1 = new Sequence('foo', 1, 1);
         $seq2 = new Sequence('foo', 1, 2);
         $seq3 = new Sequence('foo', 2, 1);
-        $seq4 = new Sequence('foo', '1', '1');
 
         $c = new Comparator();
 
         self::assertTrue($c->diffSequence($seq1, $seq2));
         self::assertTrue($c->diffSequence($seq1, $seq3));
-        self::assertFalse($c->diffSequence($seq1, $seq4));
     }
 
     public function testRemovedSequence() : void
@@ -653,7 +651,7 @@ public function testCompareColumnCompareCaseInsensitive() : void
         $c         = new Comparator();
         $tableDiff = $c->diffTable($tableA, $tableB);
 
-        self::assertFalse($tableDiff);
+        self::assertNull($tableDiff);
     }
 
     public function testCompareIndexBasedOnPropertiesNotName() : void
@@ -690,7 +688,7 @@ public function testCompareForeignKeyBasedOnPropertiesNotName() : void
         $c         = new Comparator();
         $tableDiff = $c->diffTable($tableA, $tableB);
 
-        self::assertFalse($tableDiff);
+        self::assertNull($tableDiff);
     }
 
     public function testCompareForeignKeyRestrictNoActionAreTheSame() : void
diff --git a/tests/Doctrine/Tests/DBAL/Schema/TableDiffTest.php b/tests/Doctrine/Tests/DBAL/Schema/TableDiffTest.php
index 8d37ca1dcc6..a89a529c395 100644
--- a/tests/Doctrine/Tests/DBAL/Schema/TableDiffTest.php
+++ b/tests/Doctrine/Tests/DBAL/Schema/TableDiffTest.php
@@ -58,7 +58,7 @@ public function testReturnsNewName() : void
     {
         $tableDiff = new TableDiff('foo');
 
-        self::assertFalse($tableDiff->getNewName());
+        self::assertNull($tableDiff->getNewName());
 
         $tableDiff->newName = 'bar';