schemachanger: Turn on ADD UNIQUE WITHOUT INDEX by default and add …

…tests

pkg/sql/logictest/testdata/logic_test/alter_table

@@ -1560,7 +1560,9 @@ statement ok
 INSERT INTO unique_without_index (e, f) VALUES (1, 1), (1, 2)
 
 # But trying to add a unique constraint now fails.
-statement error pgcode 23505 pq: could not create unique constraint "my_unique_e"\nDETAIL: Key \(e\)=\(1\) is duplicated\.
+# Note that we omit the constraint name in the expected error message because if the declarative schema changer is used,
+# the constraint name, at the time of validation failure, is still a place-holder name.
+statement error pgcode 23505 pq: could not create unique constraint ".*"\nDETAIL: Key \(e\)=\(1\) is duplicated\.
 ALTER TABLE unique_without_index ADD CONSTRAINT my_unique_e UNIQUE WITHOUT INDEX (e)
 
 # We can create not-valid constraints, however.
@@ -1603,11 +1605,14 @@ SELECT usage_count
  WHERE feature_name = 'sql.schema_changer.errors.constraint_violation';
 
 # Trying to add a partial unique constraint fails when there are duplicates.
-statement error pgcode 23505 pq: could not create unique constraint "uniq_a_1"\nDETAIL: Key \(a\)=\(1\) is duplicated\.
+statement error pgcode 23505 pq: could not create unique constraint ".*"\nDETAIL: Key \(a\)=\(1\) is duplicated\.
 ALTER TABLE unique_without_index_partial ADD CONSTRAINT uniq_a_1 UNIQUE WITHOUT INDEX (a) WHERE b > 0 OR c > 0
 
 # Sanity: Check the number of user errors and
 # database errors in the test.
+# We only do this check for the legacy schema changer because the declarative schema changer does not increment
+# exactly the same counters.
+onlyif config local-legacy-schema-changer
 query B
 SELECT usage_count > $constraint_violations_before
   FROM crdb_internal.feature_usage

pkg/sql/schema_changer_test.go

@@ -5627,6 +5627,7 @@ func TestTableValidityWhileAddingUniqueConstraint(t *testing.T) {
 	if _, err := sqlDB.Exec(`
 CREATE DATABASE t;
 CREATE TABLE t.tab (a INT PRIMARY KEY, b INT, c INT);
+SET use_declarative_schema_changer = off;
 `); err != nil {
 		t.Fatal(err)
 	}

pkg/sql/schemachanger/scbuild/internal/scbuildstmt/alter_table.go

@@ -54,6 +54,8 @@ var supportedAlterTableStatements = map[reflect.Type]supportedAlterTableCommand{
 		// Support ALTER TABLE ... ADD PRIMARY KEY
 		if d, ok := t.ConstraintDef.(*tree.UniqueConstraintTableDef); ok && d.PrimaryKey && t.ValidationBehavior == tree.ValidationDefault {
 			return true
+		} else if ok && d.WithoutIndex && t.ValidationBehavior == tree.ValidationDefault {
+			return true
 		}
 
 		// Support ALTER TABLE ... ADD CONSTRAINT CHECK
@@ -75,9 +77,10 @@ var supportedAlterTableStatements = map[reflect.Type]supportedAlterTableCommand{
 // They key is constructed as "ADD" + constraint type + validation behavior, joined with "_".
 // E.g. "ADD_PRIMARY_KEY_DEFAULT", "ADD_CHECK_SKIP", "ADD_FOREIGN_KEY_DEFAULT", etc.
 var alterTableAddConstraintMinSupportedClusterVersion = map[string]clusterversion.Key{
-	"ADD_PRIMARY_KEY_DEFAULT": clusterversion.V22_2Start,
-	"ADD_CHECK_DEFAULT":       clusterversion.V23_1Start,
-	"ADD_FOREIGN_KEY_DEFAULT": clusterversion.V23_1Start,
+	"ADD_PRIMARY_KEY_DEFAULT":          clusterversion.V22_2Start,
+	"ADD_CHECK_DEFAULT":                clusterversion.V23_1Start,
+	"ADD_FOREIGN_KEY_DEFAULT":          clusterversion.V23_1Start,
+	"ADD_UNIQUE_WITHOUT_INDEX_DEFAULT": clusterversion.V23_1Start,
 }
 
 func init() {
@@ -166,6 +169,8 @@ func alterTableAddConstraintSupportedInCurrentClusterVersion(
 	case *tree.UniqueConstraintTableDef:
 		if d.PrimaryKey {
 			cmdKey = "ADD_PRIMARY_KEY"
+		} else if d.WithoutIndex {
+			cmdKey = "ADD_UNIQUE_WITHOUT_INDEX"
 		}
 	case *tree.CheckConstraintTableDef:
 		cmdKey = "ADD_CHECK"

pkg/sql/schemachanger/scplan/internal/rules/helpers.go

@@ -375,7 +375,7 @@ func isIndexDependent(e scpb.Element) bool {
 // when we properly support adding/dropping them in the new schema changer.
 func isSupportedNonIndexBackedConstraint(e scpb.Element) bool {
 	switch e.(type) {
-	case *scpb.CheckConstraint, *scpb.ForeignKeyConstraint:
+	case *scpb.CheckConstraint, *scpb.ForeignKeyConstraint, *scpb.UniqueWithoutIndexConstraint:
 		return true
 	}
 	return false