Fix adding extra unique constraint to columns that are already unique

pkg/migrations/op_create_constraint_test.go

@@ -495,6 +495,106 @@ func TestCreateConstraint(t *testing.T) {
 				}, rows)
 			},
 		},
+		{
+			name: "create unique constraint on a unique column and another column",
+			migrations: []migrations.Migration{
+				{
+					Name: "01_add_table",
+					Operations: migrations.Operations{
+						&migrations.OpCreateTable{
+							Name: "users",
+							Columns: []migrations.Column{
+								{
+									Name: "id",
+									Type: "serial",
+									Pk:   true,
+								},
+								{
+									Name:     "name",
+									Type:     "varchar(255)",
+									Nullable: false,
+								},
+								{
+									Name:     "email",
+									Type:     "varchar(255)",
+									Nullable: true,
+								},
+							},
+							Constraints: []migrations.Constraint{
+								{
+									Name:    "unique_name",
+									Type:    "unique",
+									Columns: []string{"name"},
+								},
+							},
+						},
+					},
+				},
+				{
+					Name: "02_create_constraint",
+					Operations: migrations.Operations{
+						&migrations.OpCreateConstraint{
+							Name:    "unique_name_email",
+							Table:   "users",
+							Type:    "unique",
+							Columns: []string{"email", "name"},
+							Up: map[string]string{
+								"name":  "name || random()",
+								"email": "email || random()",
+							},
+							Down: map[string]string{
+								"name":  "name",
+								"email": "email",
+							},
+						},
+					},
+				},
+			},
+			afterStart: func(t *testing.T, db *sql.DB, schema string) {
+				// The index has been created on the underlying table.
+				IndexMustExist(t, db, schema, "users", "unique_name")
+				IndexMustExist(t, db, schema, "users", "unique_name_email")
+
+				// Inserting values into the old schema that violate uniqueness should succeed.
+				MustInsert(t, db, schema, "01_add_table", "users", map[string]string{
+					"name":  "alice",
+					"email": "email",
+				})
+				MustInsert(t, db, schema, "01_add_table", "users", map[string]string{
+					"name":  "bob",
+					"email": "email",
+				})
+
+				// Inserting values into the new schema that violate uniqueness should fail.
+				MustInsert(t, db, schema, "02_create_constraint", "users", map[string]string{
+					"name":  "cat",
+					"email": "email",
+				})
+				MustNotInsert(t, db, schema, "02_create_constraint", "users", map[string]string{
+					"name":  "cat",
+					"email": "email",
+				}, testutils.UniqueViolationErrorCode)
+			},
+			afterRollback: func(t *testing.T, db *sql.DB, schema string) {
+				// The index has been dropped from the the underlying table.
+				IndexMustNotExist(t, db, schema, "users", "unique_name_email")
+
+				// Functions, triggers and temporary columns are dropped.
+				TableMustBeCleanedUp(t, db, schema, "users", "name", "email")
+			},
+			afterComplete: func(t *testing.T, db *sql.DB, schema string) {
+				// Functions, triggers and temporary columns are dropped.
+				TableMustBeCleanedUp(t, db, schema, "users", "name", "email")
+
+				// Inserting values into the new schema that violate uniqueness should fail.
+				MustInsert(t, db, schema, "02_create_constraint", "users", map[string]string{
+					"name": "carol",
+				})
+				MustNotInsert(t, db, schema, "02_create_constraint", "users", map[string]string{
+					"name": "carol",
+				}, testutils.UniqueViolationErrorCode)
+			},
+		},
 	})
 }
 

pkg/migrations/rename.go

@@ -123,26 +123,24 @@ func RenameDuplicatedColumn(ctx context.Context, conn db.DB, table *schema.Table
 	// Rename any indexes on the duplicated column and use unique indexes to
 	// create `UNIQUE` constraints.
 	for _, idx := range table.Indexes {
-		if !IsDuplicatedName(idx.Name) {
+		if !IsDuplicatedName(idx.Name) || !slices.Contains(idx.Columns, TemporaryName(column.Name)) {
 			continue
 		}
 
-		if slices.Contains(idx.Columns, TemporaryName(column.Name)) {
-			// Rename the index to its original name
-			renameIndexSQL := fmt.Sprintf(cRenameIndexSQL,
-				pq.QuoteIdentifier(idx.Name),
-				pq.QuoteIdentifier(StripDuplicationPrefix(idx.Name)),
-			)
+		// Rename the index to its original name
+		renameIndexSQL := fmt.Sprintf(cRenameIndexSQL,
+			pq.QuoteIdentifier(idx.Name),
+			pq.QuoteIdentifier(StripDuplicationPrefix(idx.Name)),
+		)
 
-			_, err = conn.ExecContext(ctx, renameIndexSQL)
-			if err != nil {
-				return fmt.Errorf("failed to rename index %q: %w", idx.Name, err)
-			}
-
-			// Index no longer exists, remove it from the table
-			delete(table.Indexes, idx.Name)
+		_, err = conn.ExecContext(ctx, renameIndexSQL)
+		if err != nil {
+			return fmt.Errorf("failed to rename index %q: %w", idx.Name, err)
 		}
 
+		// Index no longer exists, remove it from the table
+		delete(table.Indexes, idx.Name)
+
 		if _, ok := table.UniqueConstraints[StripDuplicationPrefix(idx.Name)]; idx.Unique && ok {
 			// Create a unique constraint using the unique index
 			createUniqueConstraintSQL := fmt.Sprintf(cCreateUniqueConstraintSQL,
@@ -156,7 +154,6 @@ func RenameDuplicatedColumn(ctx context.Context, conn db.DB, table *schema.Table
 				return fmt.Errorf("failed to create unique constraint from index %q: %w", idx.Name, err)
 			}
 		}
-
 	}
 
 	return nil