Implemented a no-op node for statements that can be safely ignored

server/ast/alter_table.go

@@ -23,7 +23,7 @@
 )
 
 // nodeAlterTable handles *tree.AlterTable nodes.
-func nodeAlterTable(ctx *Context, node *tree.AlterTable) (*vitess.AlterTable, error) {
+func nodeAlterTable(ctx *Context, node *tree.AlterTable) (vitess.Statement, error) {
 	if node == nil {
 		return nil, nil
 	}
@@ -34,11 +34,21 @@
 		return nil, err
 	}
 
-	statements, err := nodeAlterTableCmds(ctx, node.Cmds, tableName, node.IfExists)
+	statements, noOps, err := nodeAlterTableCmds(ctx, node.Cmds, tableName, node.IfExists)
 	if err != nil {
 		return nil, err
 	}
 
+	// If there are no valid statements return a no-op statement
+	if len(noOps) > 0 && len(statements) == 0 {
+		return NewNoOp(noOps), nil
+	}
+
+	// Otherwise emit warnings now, then return an AlterTable statement
+	if len(noOps) > 0 {
+		// TODO: we need a sql context here to emit warnings
+	}
+
 	return &vitess.AlterTable{
 		Table:      tableName,
 		Statements: statements,
@@ -53,54 +63,87 @@
 	return nil, fmt.Errorf("ALTER TABLE SET SCHEMA is not yet supported")
 }
 
-// nodeAlterTableCmds converts tree.AlterTableCmds into a slice of vitess.DDL
-// instances that can be executed by GMS. |tableName| identifies the table
-// being altered, and |ifExists| indicates whether the IF EXISTS clause was
-// specified.
+// nodeAlterTableCmds converts tree.AlterTableCmds into a slice of vitess.DDL instances that can be executed by GMS.
+// |tableName| identifies the table being altered, and |ifExists| indicates whether the IF EXISTS clause was specified.
+// A second slice of unsupported but safely ignored statements is return as well.
 func nodeAlterTableCmds(
 	ctx *Context,
 	node tree.AlterTableCmds,
 	tableName vitess.TableName,
-	ifExists bool) ([]*vitess.DDL, error) {
+	ifExists bool) ([]*vitess.DDL, []string, error) {
 
 	if len(node) == 0 {
-		return nil, fmt.Errorf("no commands specified for ALTER TABLE statement")
+		return nil, nil, fmt.Errorf("no commands specified for ALTER TABLE statement")
 	}
 
 	vitessDdlCmds := make([]*vitess.DDL, 0, len(node))
+	var unsupportedWarnings []string
 	for _, cmd := range node {
 		var err error
 		var statement *vitess.DDL
 		switch cmd := cmd.(type) {
 		case *tree.AlterTableAddConstraint:
 			statement, err = nodeAlterTableAddConstraint(ctx, cmd, tableName, ifExists)
+			if err != nil {
+				return nil, nil, err
+			}
+			vitessDdlCmds = append(vitessDdlCmds, statement)
 		case *tree.AlterTableAddColumn:
 			statement, err = nodeAlterTableAddColumn(ctx, cmd, tableName, ifExists)
+			if err != nil {
+				return nil, nil, err
+			}
+			vitessDdlCmds = append(vitessDdlCmds, statement)
 		case *tree.AlterTableDropColumn:
 			statement, err = nodeAlterTableDropColumn(ctx, cmd, tableName, ifExists)
+			if err != nil {
+				return nil, nil, err
+			}
+			vitessDdlCmds = append(vitessDdlCmds, statement)
 		case *tree.AlterTableDropConstraint:
 			statement, err = nodeAlterTableDropConstraint(ctx, cmd, tableName, ifExists)
+			if err != nil {
+				return nil, nil, err
+			}
+			vitessDdlCmds = append(vitessDdlCmds, statement)
 		case *tree.AlterTableRenameColumn:
 			statement, err = nodeAlterTableRenameColumn(ctx, cmd, tableName, ifExists)
+			if err != nil {
+				return nil, nil, err
+			}
+			vitessDdlCmds = append(vitessDdlCmds, statement)
 		case *tree.AlterTableSetDefault:
 			statement, err = nodeAlterTableSetDefault(ctx, cmd, tableName, ifExists)
+			if err != nil {
+				return nil, nil, err
+			}
+			vitessDdlCmds = append(vitessDdlCmds, statement)
 		case *tree.AlterTableDropNotNull:
 			statement, err = nodeAlterTableDropNotNull(ctx, cmd, tableName, ifExists)
+			if err != nil {
+				return nil, nil, err
+			}
+			vitessDdlCmds = append(vitessDdlCmds, statement)
 		case *tree.AlterTableSetNotNull:
 			statement, err = nodeAlterTableSetNotNull(ctx, cmd, tableName, ifExists)
+			if err != nil {
+				return nil, nil, err
+			}
+			vitessDdlCmds = append(vitessDdlCmds, statement)
 		case *tree.AlterTableAlterColumnType:
 			statement, err = nodeAlterTableAlterColumnType(ctx, cmd, tableName, ifExists)
+			if err != nil {
+				return nil, nil, err
+			}
+			vitessDdlCmds = append(vitessDdlCmds, statement)
+		case *tree.AlterTableOwner:
+			unsupportedWarnings = append(unsupportedWarnings, fmt.Sprintf("ALTER TABLE %s OWNER TO %s", tableName.String(), cmd.Owner))
 		default:
-			return nil, fmt.Errorf("ALTER TABLE with unsupported command type %T", cmd)
-		}
-
-		if err != nil {
-			return nil, err
+			return nil, nil, fmt.Errorf("ALTER TABLE with unsupported command type %T", cmd)
 		}
-		vitessDdlCmds = append(vitessDdlCmds, statement)
 	}
 
-	return vitessDdlCmds, nil
+	return vitessDdlCmds, unsupportedWarnings, nil
 }
 
 // nodeAlterTableAddConstraint converts a tree.AlterTableAddConstraint instance

server/ast/no_op.go

@@ -0,0 +1,29 @@
+// Copyright 2025 Dolthub, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ast
+
+import (
+	vitess "github.com/dolthub/vitess/go/vt/sqlparser"
+
+	pgnodes "github.com/dolthub/doltgresql/server/node"
+)
+
+func NewNoOp(warnings []string) vitess.InjectedStatement {
+	return vitess.InjectedStatement{
+		Statement: pgnodes.NoOp{
+			Warnings: warnings,
+		},
+	}
+}

server/node/no_op.go

@@ -0,0 +1,77 @@
+// Copyright 2025 Dolthub, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package node
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/dolthub/go-mysql-server/sql"
+	vitess "github.com/dolthub/vitess/go/vt/sqlparser"
+)
+
+var _ vitess.Injectable = (*NoOp)(nil)
+var _ sql.ExecSourceRel = (*NoOp)(nil)
+
+type NoOp struct {
+	Warnings []string
+}
+
+func (n NoOp) Resolved() bool {
+	return true
+}
+
+func (n NoOp) String() string {
+	return fmt.Sprintf("%v", n.Warnings)
+}
+
+func (n NoOp) Schema() sql.Schema {
+	return nil
+}
+
+func (n NoOp) Children() []sql.Node {
+	return nil
+}
+
+func (n NoOp) WithChildren(children ...sql.Node) (sql.Node, error) {
+	return n, nil
+}
+
+func (n NoOp) IsReadOnly() bool {
+	return true
+}
+
+func (n NoOp) WithResolvedChildren(children []any) (any, error) {
+	return n, nil
+}
+
+type noOpRowIter struct {
+	warnings []string
+}
+
+func (n noOpRowIter) Next(ctx *sql.Context) (sql.Row, error) {
+	return nil, io.EOF
+}
+
+func (n noOpRowIter) Close(ctx *sql.Context) error {
+	for _, warning := range n.warnings {
+		ctx.Warn(0, fmt.Sprintf("%s is unimplemented", warning))
+	}
+	return nil
+}
+
+func (n NoOp) RowIter(ctx *sql.Context, r sql.Row) (sql.RowIter, error) {
+	return noOpRowIter{warnings: n.Warnings}, nil
+}

testing/go/alter_table_test.go

@@ -417,5 +417,16 @@ func TestAlterTable(t *testing.T) {
 				},
 			},
 		},
+		{
+			Name: "alter table owner",
+			SetUpScript: []string{
+				"CREATE TABLE t1 (a INT, b INT);",
+			},
+			Assertions: []ScriptTestAssertion{
+				{
+					Query: "ALTER TABLE t1 OWNER TO new_owner;", // no error is all we expect here
+				},
+			},
+		},
 	})
 }