diff --git a/src/Cache/ArrayStatement.php b/src/Cache/ArrayStatement.php
index 73aed53c9da..8227c9fc2cf 100644
--- a/src/Cache/ArrayStatement.php
+++ b/src/Cache/ArrayStatement.php
@@ -26,9 +26,6 @@ final class ArrayStatement implements IteratorAggregate, ResultStatement
     /** @var int */
     private $num = 0;
 
-    /** @var int */
-    private $defaultFetchMode = FetchMode::MIXED;
-
     /**
      * @param mixed[] $data
      */
@@ -57,11 +54,6 @@ public function rowCount() : int
         return count($this->data);
     }
 
-    public function setFetchMode(int $fetchMode) : void
-    {
-        $this->defaultFetchMode = $fetchMode;
-    }
-
     /**
      * {@inheritdoc}
      */
@@ -75,14 +67,13 @@ public function getIterator()
     /**
      * {@inheritdoc}
      */
-    public function fetch(?int $fetchMode = null)
+    public function fetch(int $fetchMode = FetchMode::ASSOCIATIVE)
     {
         if (! isset($this->data[$this->num])) {
             return false;
         }
 
-        $row       = $this->data[$this->num++];
-        $fetchMode = $fetchMode ?? $this->defaultFetchMode;
+        $row = $this->data[$this->num++];
 
         if ($fetchMode === FetchMode::ASSOCIATIVE) {
             return $row;
@@ -108,7 +99,7 @@ public function fetch(?int $fetchMode = null)
     /**
      * {@inheritdoc}
      */
-    public function fetchAll(?int $fetchMode = null) : array
+    public function fetchAll(int $fetchMode = FetchMode::ASSOCIATIVE) : array
     {
         $rows = [];
         while ($row = $this->fetch($fetchMode)) {
diff --git a/src/Cache/ResultCacheStatement.php b/src/Cache/ResultCacheStatement.php
index eea7233620e..bb36ab3f631 100644
--- a/src/Cache/ResultCacheStatement.php
+++ b/src/Cache/ResultCacheStatement.php
@@ -54,9 +54,6 @@ final class ResultCacheStatement implements IteratorAggregate, ResultStatement
     /** @var mixed[] */
     private $data;
 
-    /** @var int */
-    private $defaultFetchMode = FetchMode::MIXED;
-
     public function __construct(ResultStatement $stmt, Cache $resultCache, string $cacheKey, string $realKey, int $lifetime)
     {
         $this->statement   = $stmt;
@@ -90,11 +87,6 @@ public function columnCount() : int
         return $this->statement->columnCount();
     }
 
-    public function setFetchMode(int $fetchMode) : void
-    {
-        $this->defaultFetchMode = $fetchMode;
-    }
-
     /**
      * {@inheritdoc}
      */
@@ -108,7 +100,7 @@ public function getIterator()
     /**
      * {@inheritdoc}
      */
-    public function fetch(?int $fetchMode = null)
+    public function fetch(int $fetchMode = FetchMode::ASSOCIATIVE)
     {
         if ($this->data === null) {
             $this->data = [];
@@ -119,8 +111,6 @@ public function fetch(?int $fetchMode = null)
         if ($row !== false) {
             $this->data[] = $row;
 
-            $fetchMode = $fetchMode ?? $this->defaultFetchMode;
-
             if ($fetchMode === FetchMode::ASSOCIATIVE) {
                 return $row;
             }
@@ -148,7 +138,7 @@ public function fetch(?int $fetchMode = null)
     /**
      * {@inheritdoc}
      */
-    public function fetchAll(?int $fetchMode = null) : array
+    public function fetchAll(int $fetchMode = FetchMode::ASSOCIATIVE) : array
     {
         $data = $this->statement->fetchAll($fetchMode);
 
diff --git a/src/Connection.php b/src/Connection.php
index be5ec58c01d..0aed956b5d1 100644
--- a/src/Connection.php
+++ b/src/Connection.php
@@ -148,9 +148,6 @@ class Connection implements DriverConnection
      */
     private $isRollbackOnly = false;
 
-    /** @var int */
-    protected $defaultFetchMode = FetchMode::ASSOCIATIVE;
-
     /**
      * Initializes a new instance of the Connection class.
      *
@@ -446,14 +443,6 @@ public function setAutoCommit(bool $autoCommit) : void
         $this->commitAll();
     }
 
-    /**
-     * Sets the fetch mode.
-     */
-    public function setFetchMode(int $fetchMode) : void
-    {
-        $this->defaultFetchMode = $fetchMode;
-    }
-
     /**
      * Prepares and executes an SQL query and returns the first row of the result
      * as an associative array.
@@ -760,14 +749,10 @@ public function fetchAll(string $query, array $params = [], array $types = []) :
     public function prepare(string $sql) : DriverStatement
     {
         try {
-            $stmt = new Statement($sql, $this);
+            return new Statement($sql, $this);
         } catch (Throwable $ex) {
             throw DBALException::driverExceptionDuringQuery($this->_driver, $ex, $sql);
         }
-
-        $stmt->setFetchMode($this->defaultFetchMode);
-
-        return $stmt;
     }
 
     /**
@@ -818,8 +803,6 @@ public function executeQuery(
             throw DBALException::driverExceptionDuringQuery($this->_driver, $ex, $query, $this->resolveParams($params, $types));
         }
 
-        $stmt->setFetchMode($this->defaultFetchMode);
-
         $logger->stopQuery();
 
         return $stmt;
@@ -864,8 +847,6 @@ public function executeCacheQuery(string $query, array $params, array $types, Qu
             $stmt = new ResultCacheStatement($this->executeQuery($query, $params, $types), $resultCache, $cacheKey, $realKey, $qcp->getLifetime());
         }
 
-        $stmt->setFetchMode($this->defaultFetchMode);
-
         return $stmt;
     }
 
@@ -882,8 +863,6 @@ public function query(string $sql) : ResultStatement
             throw DBALException::driverExceptionDuringQuery($this->_driver, $ex, $sql);
         }
 
-        $statement->setFetchMode($this->defaultFetchMode);
-
         $logger->stopQuery();
 
         return $statement;
diff --git a/src/Connections/MasterSlaveConnection.php b/src/Connections/MasterSlaveConnection.php
index 0e808c2f589..d2b9f27d893 100644
--- a/src/Connections/MasterSlaveConnection.php
+++ b/src/Connections/MasterSlaveConnection.php
@@ -324,8 +324,6 @@ public function query(string $sql) : ResultStatement
 
         $statement = $this->_conn->query($sql);
 
-        $statement->setFetchMode($this->defaultFetchMode);
-
         $logger->stopQuery();
 
         return $statement;
diff --git a/src/Driver/IBMDB2/DB2Statement.php b/src/Driver/IBMDB2/DB2Statement.php
index c4949a3a871..3e789f54f8e 100644
--- a/src/Driver/IBMDB2/DB2Statement.php
+++ b/src/Driver/IBMDB2/DB2Statement.php
@@ -49,9 +49,6 @@ final class DB2Statement implements IteratorAggregate, Statement
      */
     private $lobs = [];
 
-    /** @var int */
-    private $defaultFetchMode = FetchMode::MIXED;
-
     /**
      * Indicates whether the statement is in the state when fetching results is possible
      *
@@ -171,11 +168,6 @@ public function execute(?array $params = null) : void
         $this->result = true;
     }
 
-    public function setFetchMode(int $fetchMode) : void
-    {
-        $this->defaultFetchMode = $fetchMode;
-    }
-
     /**
      * {@inheritdoc}
      */
@@ -187,7 +179,7 @@ public function getIterator()
     /**
      * {@inheritdoc}
      */
-    public function fetch(?int $fetchMode = null)
+    public function fetch(int $fetchMode = FetchMode::ASSOCIATIVE)
     {
         // do not try fetching from the statement if it's not expected to contain result
         // in order to prevent exceptional situation
@@ -195,7 +187,6 @@ public function fetch(?int $fetchMode = null)
             return false;
         }
 
-        $fetchMode = $fetchMode ?? $this->defaultFetchMode;
         switch ($fetchMode) {
             case FetchMode::COLUMN:
                 return $this->fetchColumn();
@@ -217,7 +208,7 @@ public function fetch(?int $fetchMode = null)
     /**
      * {@inheritdoc}
      */
-    public function fetchAll(?int $fetchMode = null) : array
+    public function fetchAll(int $fetchMode = FetchMode::ASSOCIATIVE) : array
     {
         $rows = [];
 
diff --git a/src/Driver/Mysqli/MysqliStatement.php b/src/Driver/Mysqli/MysqliStatement.php
index 8f09aeda8c4..0196c1ef028 100644
--- a/src/Driver/Mysqli/MysqliStatement.php
+++ b/src/Driver/Mysqli/MysqliStatement.php
@@ -89,9 +89,6 @@ final class MysqliStatement implements IteratorAggregate, Statement
      */
     private $values = [];
 
-    /** @var int */
-    private $defaultFetchMode = FetchMode::MIXED;
-
     /**
      * Indicates whether the statement is in the state when fetching results is possible
      *
@@ -326,7 +323,7 @@ private function _fetch()
     /**
      * {@inheritdoc}
      */
-    public function fetch(?int $fetchMode = null)
+    public function fetch(int $fetchMode = FetchMode::ASSOCIATIVE)
     {
         // do not try fetching from the statement if it's not expected to contain result
         // in order to prevent exceptional situation
@@ -334,8 +331,6 @@ public function fetch(?int $fetchMode = null)
             return false;
         }
 
-        $fetchMode = $fetchMode ?? $this->defaultFetchMode;
-
         if ($fetchMode === FetchMode::COLUMN) {
             return $this->fetchColumn();
         }
@@ -372,10 +367,8 @@ public function fetch(?int $fetchMode = null)
     /**
      * {@inheritdoc}
      */
-    public function fetchAll(?int $fetchMode = null) : array
+    public function fetchAll(int $fetchMode = FetchMode::ASSOCIATIVE) : array
     {
-        $fetchMode = $fetchMode ?? $this->defaultFetchMode;
-
         $rows = [];
 
         if ($fetchMode === FetchMode::COLUMN) {
@@ -425,11 +418,6 @@ public function columnCount() : int
         return $this->stmt->field_count;
     }
 
-    public function setFetchMode(int $fetchMode) : void
-    {
-        $this->defaultFetchMode = $fetchMode;
-    }
-
     /**
      * {@inheritdoc}
      */
diff --git a/src/Driver/OCI8/OCI8Statement.php b/src/Driver/OCI8/OCI8Statement.php
index a3a75e7ece1..36991502ab2 100644
--- a/src/Driver/OCI8/OCI8Statement.php
+++ b/src/Driver/OCI8/OCI8Statement.php
@@ -32,6 +32,7 @@
 use const OCI_D_LOB;
 use const OCI_FETCHSTATEMENT_BY_COLUMN;
 use const OCI_FETCHSTATEMENT_BY_ROW;
+use const OCI_NO_AUTO_COMMIT;
 use const OCI_NUM;
 use const OCI_RETURN_LOBS;
 use const OCI_RETURN_NULLS;
@@ -60,9 +61,6 @@ final class OCI8Statement implements IteratorAggregate, Statement
         FetchMode::COLUMN      => OCI_NUM,
     ];
 
-    /** @var int */
-    protected $_defaultFetchMode = FetchMode::MIXED;
-
     /** @var string[] */
     protected $_paramMap = [];
 
@@ -219,11 +217,6 @@ public function execute(?array $params = null) : void
         $this->result = true;
     }
 
-    public function setFetchMode(int $fetchMode) : void
-    {
-        $this->_defaultFetchMode = $fetchMode;
-    }
-
     /**
      * {@inheritdoc}
      */
@@ -235,7 +228,7 @@ public function getIterator()
     /**
      * {@inheritdoc}
      */
-    public function fetch(?int $fetchMode = null)
+    public function fetch(int $fetchMode = FetchMode::ASSOCIATIVE)
     {
         // do not try fetching from the statement if it's not expected to contain result
         // in order to prevent exceptional situation
@@ -243,8 +236,6 @@ public function fetch(?int $fetchMode = null)
             return false;
         }
 
-        $fetchMode = $fetchMode ?? $this->_defaultFetchMode;
-
         if ($fetchMode === FetchMode::COLUMN) {
             return $this->fetchColumn();
         }
@@ -262,10 +253,8 @@ public function fetch(?int $fetchMode = null)
     /**
      * {@inheritdoc}
      */
-    public function fetchAll(?int $fetchMode = null) : array
+    public function fetchAll(int $fetchMode = FetchMode::ASSOCIATIVE) : array
     {
-        $fetchMode = $fetchMode ?? $this->_defaultFetchMode;
-
         $result = [];
 
         if (! isset(self::$fetchModeMap[$fetchMode])) {
diff --git a/src/Driver/PDOConnection.php b/src/Driver/PDOConnection.php
index fcfc7caf5ee..023741330b5 100644
--- a/src/Driver/PDOConnection.php
+++ b/src/Driver/PDOConnection.php
@@ -92,6 +92,8 @@ public function lastInsertId(?string $name = null) : string
      */
     protected function createStatement(\PDOStatement $stmt) : PDOStatement
     {
+        $stmt->setFetchMode(PDO::FETCH_ASSOC);
+
         return new PDOStatement($stmt);
     }
 
diff --git a/src/Driver/PDOStatement.php b/src/Driver/PDOStatement.php
index be2552fa469..b9667f41dd6 100644
--- a/src/Driver/PDOStatement.php
+++ b/src/Driver/PDOStatement.php
@@ -46,17 +46,6 @@ public function __construct(\PDOStatement $stmt)
         $this->stmt = $stmt;
     }
 
-    public function setFetchMode(int $fetchMode) : void
-    {
-        $fetchMode = $this->convertFetchMode($fetchMode);
-
-        try {
-            $this->stmt->setFetchMode($fetchMode);
-        } catch (\PDOException $exception) {
-            throw new PDOException($exception);
-        }
-    }
-
     /**
      * {@inheritdoc}
      */
@@ -122,13 +111,9 @@ public function rowCount() : int
     /**
      * {@inheritdoc}
      */
-    public function fetch(?int $fetchMode = null)
+    public function fetch(int $fetchMode = FetchMode::ASSOCIATIVE)
     {
         try {
-            if ($fetchMode === null) {
-                return $this->stmt->fetch();
-            }
-
             return $this->stmt->fetch(
                 $this->convertFetchMode($fetchMode)
             );
@@ -140,16 +125,12 @@ public function fetch(?int $fetchMode = null)
     /**
      * {@inheritdoc}
      */
-    public function fetchAll(?int $fetchMode = null) : array
+    public function fetchAll(int $fetchMode = FetchMode::ASSOCIATIVE) : array
     {
         try {
-            if ($fetchMode === null) {
-                $data = $this->stmt->fetchAll();
-            } else {
-                $data = $this->stmt->fetchAll(
-                    $this->convertFetchMode($fetchMode)
-                );
-            }
+            $data = $this->stmt->fetchAll(
+                $this->convertFetchMode($fetchMode)
+            );
         } catch (\PDOException $exception) {
             throw new PDOException($exception);
         }
diff --git a/src/Driver/ResultStatement.php b/src/Driver/ResultStatement.php
index 1bc40dfaf39..eb4ac70871f 100644
--- a/src/Driver/ResultStatement.php
+++ b/src/Driver/ResultStatement.php
@@ -4,6 +4,7 @@
 
 namespace Doctrine\DBAL\Driver;
 
+use Doctrine\DBAL\FetchMode;
 use Traversable;
 
 /**
@@ -37,35 +38,25 @@ public function columnCount() : int;
     public function rowCount() : int;
 
     /**
-     * Sets the fetch mode to use while iterating this statement.
+     * Returns the next row of a result set.
      *
      * @param int $fetchMode Controls how the next row will be returned to the caller.
      *                       The value must be one of the {@link \Doctrine\DBAL\FetchMode} constants.
-     */
-    public function setFetchMode(int $fetchMode) : void;
-
-    /**
-     * Returns the next row of a result set.
-     *
-     * @param int|null $fetchMode Controls how the next row will be returned to the caller.
-     *                            The value must be one of the {@link \Doctrine\DBAL\FetchMode} constants,
-     *                            defaulting to {@link \Doctrine\DBAL\FetchMode::MIXED}.
      *
      * @return mixed The return value of this method on success depends on the fetch mode. In all cases, FALSE is
      *               returned on failure.
      */
-    public function fetch(?int $fetchMode = null);
+    public function fetch(int $fetchMode = FetchMode::ASSOCIATIVE);
 
     /**
      * Returns an array containing all of the result set rows.
      *
-     * @param int|null $fetchMode Controls how the next row will be returned to the caller.
-     *                            The value must be one of the {@link \Doctrine\DBAL\FetchMode} constants,
-     *                            defaulting to {@link \Doctrine\DBAL\FetchMode::MIXED}.
+     * @param int $fetchMode Controls how the next row will be returned to the caller.
+     *                       The value must be one of the {@link \Doctrine\DBAL\FetchMode} constants.
      *
      * @return mixed[]
      */
-    public function fetchAll(?int $fetchMode = null) : array;
+    public function fetchAll(int $fetchMode = FetchMode::ASSOCIATIVE) : array;
 
     /**
      * Returns a single column from the next row of a result set or FALSE if there are no more rows.
diff --git a/src/Driver/SQLAnywhere/SQLAnywhereStatement.php b/src/Driver/SQLAnywhere/SQLAnywhereStatement.php
index fd0d39b7986..11553be7b42 100644
--- a/src/Driver/SQLAnywhere/SQLAnywhereStatement.php
+++ b/src/Driver/SQLAnywhere/SQLAnywhereStatement.php
@@ -35,9 +35,6 @@ final class SQLAnywhereStatement implements IteratorAggregate, Statement
     /** @var resource The connection resource. */
     private $conn;
 
-    /** @var int Default fetch mode to use. */
-    private $defaultFetchMode = FetchMode::MIXED;
-
     /** @var resource|null The result set resource to fetch. */
     private $result;
 
@@ -157,14 +154,12 @@ public function execute(?array $params = null) : void
      *
      * @throws SQLAnywhereException
      */
-    public function fetch(?int $fetchMode = null)
+    public function fetch(int $fetchMode = FetchMode::ASSOCIATIVE)
     {
         if (! is_resource($this->result)) {
             return false;
         }
 
-        $fetchMode = $fetchMode ?? $this->defaultFetchMode;
-
         switch ($fetchMode) {
             case FetchMode::COLUMN:
                 return $this->fetchColumn();
@@ -186,7 +181,7 @@ public function fetch(?int $fetchMode = null)
     /**
      * {@inheritdoc}
      */
-    public function fetchAll(?int $fetchMode = null) : array
+    public function fetchAll(int $fetchMode = FetchMode::ASSOCIATIVE) : array
     {
         $rows = [];
 
@@ -233,9 +228,4 @@ public function rowCount() : int
     {
         return sasql_stmt_affected_rows($this->stmt);
     }
-
-    public function setFetchMode(int $fetchMode) : void
-    {
-        $this->defaultFetchMode = $fetchMode;
-    }
 }
diff --git a/src/Driver/SQLSrv/SQLSrvStatement.php b/src/Driver/SQLSrv/SQLSrvStatement.php
index 04014edc960..3f5545ce668 100644
--- a/src/Driver/SQLSrv/SQLSrvStatement.php
+++ b/src/Driver/SQLSrv/SQLSrvStatement.php
@@ -80,13 +80,6 @@ final class SQLSrvStatement implements IteratorAggregate, Statement
         FetchMode::NUMERIC     => SQLSRV_FETCH_NUMERIC,
     ];
 
-    /**
-     * The fetch style.
-     *
-     * @var int
-     */
-    private $defaultFetchMode = FetchMode::MIXED;
-
     /**
      * The last insert ID.
      *
@@ -211,11 +204,6 @@ public function execute(?array $params = null) : void
         $this->result = true;
     }
 
-    public function setFetchMode(int $fetchMode) : void
-    {
-        $this->defaultFetchMode = $fetchMode;
-    }
-
     /**
      * {@inheritdoc}
      */
@@ -229,7 +217,7 @@ public function getIterator()
      *
      * @throws SQLSrvException
      */
-    public function fetch(?int $fetchMode = null)
+    public function fetch(int $fetchMode = FetchMode::ASSOCIATIVE)
     {
         // do not try fetching from the statement if it's not expected to contain result
         // in order to prevent exceptional situation
@@ -237,8 +225,6 @@ public function fetch(?int $fetchMode = null)
             return false;
         }
 
-        $fetchMode = $fetchMode ?? $this->defaultFetchMode;
-
         if ($fetchMode === FetchMode::COLUMN) {
             return $this->fetchColumn();
         }
@@ -253,7 +239,7 @@ public function fetch(?int $fetchMode = null)
     /**
      * {@inheritdoc}
      */
-    public function fetchAll(?int $fetchMode = null) : array
+    public function fetchAll(int $fetchMode = FetchMode::ASSOCIATIVE) : array
     {
         $rows = [];
 
diff --git a/src/Portability/Connection.php b/src/Portability/Connection.php
index 794725edbdd..9e287bb0d36 100644
--- a/src/Portability/Connection.php
+++ b/src/Portability/Connection.php
@@ -99,28 +99,20 @@ public function executeQuery(
         array $types = [],
         ?QueryCacheProfile $qcp = null
     ) : ResultStatement {
-        $stmt = new Statement(parent::executeQuery($query, $params, $types, $qcp), $this);
-        $stmt->setFetchMode($this->defaultFetchMode);
-
-        return $stmt;
+        return new Statement(parent::executeQuery($query, $params, $types, $qcp), $this);
     }
 
     public function prepare(string $sql) : DriverStatement
     {
-        $stmt = new Statement(parent::prepare($sql), $this);
-        $stmt->setFetchMode($this->defaultFetchMode);
-
-        return $stmt;
+        return new Statement(parent::prepare($sql), $this);
     }
 
     public function query(string $sql) : ResultStatement
     {
-        $connection = $this->getWrappedConnection();
-
-        $stmt = $connection->query($sql);
-        $stmt = new Statement($stmt, $this);
-        $stmt->setFetchMode($this->defaultFetchMode);
-
-        return $stmt;
+        return new Statement(
+            $this->getWrappedConnection()
+                ->query($sql),
+            $this
+        );
     }
 }
diff --git a/src/Portability/Statement.php b/src/Portability/Statement.php
index 80f160af3b2..2889eb2ce59 100644
--- a/src/Portability/Statement.php
+++ b/src/Portability/Statement.php
@@ -29,9 +29,6 @@ final class Statement implements IteratorAggregate, DriverStatement
     /** @var int|null */
     private $case;
 
-    /** @var int */
-    private $defaultFetchMode = FetchMode::MIXED;
-
     /**
      * Wraps <tt>Statement</tt> and applies portability measures.
      *
@@ -84,13 +81,6 @@ public function execute(?array $params = null) : void
         $this->stmt->execute($params);
     }
 
-    public function setFetchMode(int $fetchMode) : void
-    {
-        $this->defaultFetchMode = $fetchMode;
-
-        $this->stmt->setFetchMode($fetchMode);
-    }
-
     /**
      * {@inheritdoc}
      */
@@ -102,10 +92,8 @@ public function getIterator()
     /**
      * {@inheritdoc}
      */
-    public function fetch(?int $fetchMode = null)
+    public function fetch(int $fetchMode = FetchMode::ASSOCIATIVE)
     {
-        $fetchMode = $fetchMode ?? $this->defaultFetchMode;
-
         $row = $this->stmt->fetch($fetchMode);
 
         $iterateRow = ($this->portability & (Connection::PORTABILITY_EMPTY_TO_NULL|Connection::PORTABILITY_RTRIM)) !== 0;
@@ -121,10 +109,8 @@ public function fetch(?int $fetchMode = null)
     /**
      * {@inheritdoc}
      */
-    public function fetchAll(?int $fetchMode = null) : array
+    public function fetchAll(int $fetchMode = FetchMode::ASSOCIATIVE) : array
     {
-        $fetchMode = $fetchMode ?? $this->defaultFetchMode;
-
         $rows = $this->stmt->fetchAll($fetchMode);
 
         $iterateRow = ($this->portability & (Connection::PORTABILITY_EMPTY_TO_NULL|Connection::PORTABILITY_RTRIM)) !== 0;
diff --git a/src/Statement.php b/src/Statement.php
index 874c80cb306..e794605ef36 100644
--- a/src/Statement.php
+++ b/src/Statement.php
@@ -180,11 +180,6 @@ public function columnCount() : int
         return $this->stmt->columnCount();
     }
 
-    public function setFetchMode(int $fetchMode) : void
-    {
-        $this->stmt->setFetchMode($fetchMode);
-    }
-
     /**
      * Required by interface IteratorAggregate.
      *
@@ -198,7 +193,7 @@ public function getIterator()
     /**
      * {@inheritdoc}
      */
-    public function fetch(?int $fetchMode = null)
+    public function fetch(int $fetchMode = FetchMode::ASSOCIATIVE)
     {
         return $this->stmt->fetch($fetchMode);
     }
@@ -206,7 +201,7 @@ public function fetch(?int $fetchMode = null)
     /**
      * {@inheritdoc}
      */
-    public function fetchAll(?int $fetchMode = null) : array
+    public function fetchAll(int $fetchMode = FetchMode::ASSOCIATIVE) : array
     {
         return $this->stmt->fetchAll($fetchMode);
     }
diff --git a/tests/Cache/ArrayStatementTest.php b/tests/Cache/ArrayStatementTest.php
index 1e23bc28e53..70d7d73be71 100644
--- a/tests/Cache/ArrayStatementTest.php
+++ b/tests/Cache/ArrayStatementTest.php
@@ -50,19 +50,9 @@ public function testRowCount() : void
         self::assertSame(2, $statement->rowCount());
     }
 
-    public function testSetFetchMode() : void
-    {
-        $statement = $this->createTestArrayStatement();
-
-        $statement->setFetchMode(FetchMode::ASSOCIATIVE);
-
-        self::assertSame($this->users[0], $statement->fetch());
-    }
-
     public function testGetIterator() : void
     {
         $statement = $this->createTestArrayStatement();
-        $statement->setFetchMode(FetchMode::ASSOCIATIVE);
 
         self::assertSame($this->users, iterator_to_array($statement->getIterator()));
     }
diff --git a/tests/Functional/DataAccessTest.php b/tests/Functional/DataAccessTest.php
index e321ae8e4ee..ffcf662873a 100644
--- a/tests/Functional/DataAccessTest.php
+++ b/tests/Functional/DataAccessTest.php
@@ -20,13 +20,10 @@
 use Doctrine\DBAL\Types\Types;
 use InvalidArgumentException;
 use function array_change_key_case;
-use function array_filter;
-use function array_keys;
 use function assert;
 use function count;
 use function date;
 use function is_array;
-use function is_numeric;
 use function json_encode;
 use function sprintf;
 use function strtotime;
@@ -161,7 +158,7 @@ public function testPrepareWithIterator() : void
         $stmt->execute();
 
         $rows = [];
-        $stmt->setFetchMode(FetchMode::ASSOCIATIVE);
+
         foreach ($stmt as $row) {
             $rows[] = array_change_key_case($row, CASE_LOWER);
         }
@@ -1041,17 +1038,6 @@ public function testBitComparisonExpressionSupport() : void
         }
     }
 
-    public function testSetDefaultFetchMode() : void
-    {
-        $stmt = $this->connection->query('SELECT * FROM fetch_table');
-        $stmt->setFetchMode(FetchMode::NUMERIC);
-
-        $row = array_keys($stmt->fetch());
-        self::assertCount(0, array_filter($row, static function ($v) : bool {
-            return ! is_numeric($v);
-        }), 'should be no non-numerical elements in the result.');
-    }
-
     /**
      * @group DBAL-241
      */
@@ -1081,22 +1067,6 @@ public function testEmptyFetchColumnReturnsFalse() : void
         $this->connection->rollBack();
     }
 
-    /**
-     * @group DBAL-339
-     */
-    public function testSetFetchModeOnDbalStatement() : void
-    {
-        $sql  = 'SELECT test_int, test_string FROM fetch_table WHERE test_int = ? AND test_string = ?';
-        $stmt = $this->connection->executeQuery($sql, [1, 'foo']);
-        $stmt->setFetchMode(FetchMode::NUMERIC);
-
-        $row = $stmt->fetch();
-
-        self::assertArrayHasKey(0, $row);
-        self::assertArrayHasKey(1, $row);
-        self::assertFalse($stmt->fetch());
-    }
-
     /**
      * @group DBAL-435
      */
diff --git a/tests/Functional/PortabilityTest.php b/tests/Functional/PortabilityTest.php
index 9828bd4e549..89aca6edbf7 100644
--- a/tests/Functional/PortabilityTest.php
+++ b/tests/Functional/PortabilityTest.php
@@ -82,7 +82,6 @@ public function testFullFetchMode() : void
         $this->assertFetchResultRows($rows);
 
         $stmt = $this->portableConnection->query('SELECT * FROM portability_table');
-        $stmt->setFetchMode(FetchMode::ASSOCIATIVE);
 
         foreach ($stmt as $row) {
             $this->assertFetchResultRow($row);
@@ -104,8 +103,6 @@ public function testFullFetchMode() : void
 
     public function testConnFetchMode() : void
     {
-        $this->portableConnection->setFetchMode(FetchMode::ASSOCIATIVE);
-
         $rows = $this->portableConnection->fetchAll('SELECT * FROM portability_table');
         $this->assertFetchResultRows($rows);
 
diff --git a/tests/Functional/ResultCacheTest.php b/tests/Functional/ResultCacheTest.php
index aafca09f694..e27bab43d0a 100644
--- a/tests/Functional/ResultCacheTest.php
+++ b/tests/Functional/ResultCacheTest.php
@@ -256,8 +256,8 @@ private function hydrateStmt(ResultStatement $stmt, int $fetchMode = FetchMode::
     private function hydrateStmtIterator(ResultStatement $stmt, int $fetchMode = FetchMode::ASSOCIATIVE) : array
     {
         $data = [];
-        $stmt->setFetchMode($fetchMode);
-        foreach ($stmt as $row) {
+
+        while (($row = $stmt->fetch($fetchMode)) !== false) {
             $data[] = is_array($row) ? array_change_key_case($row, CASE_LOWER) : $row;
         }