ddl, parser: support 'ALTER TABLE RENAME KEY TO' syntax (#6475)

ast/ddl.go

@@ -717,6 +717,7 @@ const (
 	AlterTableAlterColumn
 	AlterTableLock
 	AlterTableAlgorithm
+	AlterTableRenameIndex
 	AlterTableForce
 
 // TODO: Add more actions
@@ -748,6 +749,8 @@ type AlterTableSpec struct {
 	Position      *ColumnPosition
 	LockType      LockType
 	Comment       string
+	FromKey       model.CIStr
+	ToKey         model.CIStr
 }
 
 // Accept implements Node Accept interface.

ddl/ddl_api.go

@@ -999,6 +999,8 @@ func (d *ddl) AlterTable(ctx sessionctx.Context, ident ast.Ident, specs []*ast.A
 			err = d.RenameTable(ctx, ident, newIdent)
 		case ast.AlterTableDropPrimaryKey:
 			err = ErrUnsupportedModifyPrimaryKey.GenByArgs("drop")
+		case ast.AlterTableRenameIndex:
+			err = d.RenameIndex(ctx, ident, spec)
 		case ast.AlterTableOption:
 			for _, opt := range spec.Options {
 				switch opt.Tp {
@@ -1574,6 +1576,41 @@ func (d *ddl) AlterTableComment(ctx sessionctx.Context, ident ast.Ident, spec *a
 	return errors.Trace(err)
 }
 
+// RenameIndex renames an index.
+// In TiDB, indexes are case-insensitive (so index 'a' and 'A" are considered the same index),
+// but index names are case-sensitive (we can rename index 'a' to 'A')
+func (d *ddl) RenameIndex(ctx sessionctx.Context, ident ast.Ident, spec *ast.AlterTableSpec) error {
+	is := d.infoHandle.Get()
+	schema, ok := is.SchemaByName(ident.Schema)
+	if !ok {
+		return infoschema.ErrDatabaseNotExists.GenByArgs(ident.Schema)
+	}
+
+	tb, err := is.TableByName(ident.Schema, ident.Name)
+	if err != nil {
+		return errors.Trace(infoschema.ErrTableNotExists.GenByArgs(ident.Schema, ident.Name))
+	}
+	duplicate, err := validateRenameIndex(spec.FromKey, spec.ToKey, tb.Meta())
+	if duplicate {
+		return nil
+	}
+	if err != nil {
+		return errors.Trace(err)
+	}
+
+	job := &model.Job{
+		SchemaID:   schema.ID,
+		TableID:    tb.Meta().ID,
+		Type:       model.ActionRenameIndex,
+		BinlogInfo: &model.HistoryInfo{},
+		Args:       []interface{}{spec.FromKey, spec.ToKey},
+	}
+
+	err = d.doDDLJob(ctx, job)
+	err = d.callHookOnChanged(err)
+	return errors.Trace(err)
+}
+
 // DropTable will proceed even if some table in the list does not exists.
 func (d *ddl) DropTable(ctx sessionctx.Context, ti ast.Ident) (err error) {
 	is := d.GetInformationSchema()

ddl/ddl_db_test.go

@@ -268,6 +268,29 @@ func (s *testDBSuite) TestAddIndexWithPK(c *C) {
 	s.tk.MustQuery("select * from test_add_index_with_pk2").Check(testkit.Rows("1 1 1 1", "2 2 2 2"))
 }
 
+func (s *testDBSuite) TestRenameIndex(c *C) {
+	s.tk = testkit.NewTestKit(c, s.store)
+	s.tk.MustExec("use " + s.schemaName)
+	s.tk.MustExec("create table t (pk int primary key, c int default 1, c1 int default 1, unique key k1(c), key k2(c1))")
+
+	// Test rename success
+	s.tk.MustExec("alter table t rename index k1 to k3")
+	s.tk.MustExec("admin check index t k3")
+
+	// Test rename to the same name
+	s.tk.MustExec("alter table t rename index k3 to k3")
+	s.tk.MustExec("admin check index t k3")
+
+	// Test rename on non-exists keys
+	s.testErrorCode(c, "alter table t rename index x to x", mysql.ErrKeyDoesNotExist)
+
+	// Test rename on already-exists keys
+	s.testErrorCode(c, "alter table t rename index k3 to k2", mysql.ErrDupKeyName)
+
+	s.tk.MustExec("alter table t rename index k2 to K2")
+	s.testErrorCode(c, "alter table t rename key k3 to K2", mysql.ErrDupKeyName)
+}
+
 func (s *testDBSuite) testGetTable(c *C, name string) table.Table {
 	ctx := s.s.(sessionctx.Context)
 	dom := domain.GetDomain(ctx)

ddl/ddl_worker.go

@@ -389,6 +389,8 @@ func (d *ddl) runDDLJob(t *meta.Meta, job *model.Job) (ver int64, err error) {
 		ver, err = d.onShardRowID(t, job)
 	case model.ActionModifyTableComment:
 		ver, err = d.onModifyTableComment(t, job)
+	case model.ActionRenameIndex:
+		ver, err = d.onRenameIndex(t, job)
 	default:
 		// Invalid job, cancel it.
 		job.State = model.JobStateCancelled

ddl/index.go

@@ -19,6 +19,7 @@ import (
 
 	"github.com/juju/errors"
 	"github.com/pingcap/tidb/ast"
+	"github.com/pingcap/tidb/infoschema"
 	"github.com/pingcap/tidb/kv"
 	"github.com/pingcap/tidb/meta"
 	"github.com/pingcap/tidb/metrics"
@@ -174,6 +175,23 @@ func dropIndexColumnFlag(tblInfo *model.TableInfo, indexInfo *model.IndexInfo) {
 	}
 }
 
+func validateRenameIndex(from, to model.CIStr, tbl *model.TableInfo) (ignore bool, err error) {
+	if fromIdx := findIndexByName(from.L, tbl.Indices); fromIdx == nil {
+		return false, errors.Trace(infoschema.ErrKeyNotExists.GenByArgs(from.O, tbl.Name))
+	}
+	// Take case-sensitivity into account, if `FromKey` and  `ToKey` are the same, nothing need to be changed
+	if from.O == to.O {
+		return true, nil
+	}
+	// If spec.FromKey.L == spec.ToKey.L, we operate on the same index(case-insensitive) and change its name (case-sensitive)
+	// e.g: from `inDex` to `IndEX`. Otherwise, we try to rename an index to another different index which already exists,
+	// that's illegal by rule.
+	if toIdx := findIndexByName(to.L, tbl.Indices); toIdx != nil && from.L != to.L {
+		return false, errors.Trace(infoschema.ErrKeyNameDuplicate.GenByArgs(toIdx.Name.O))
+	}
+	return false, nil
+}
+
 func (d *ddl) onCreateIndex(t *meta.Meta, job *model.Job) (ver int64, err error) {
 	// Handle the rolling back job.
 	if job.IsRollingback() {

ddl/table.go

@@ -357,6 +357,37 @@ func (d *ddl) onModifyTableComment(t *meta.Meta, job *model.Job) (ver int64, _ e
 	return ver, nil
 }
 
+func (d *ddl) onRenameIndex(t *meta.Meta, job *model.Job) (ver int64, _ error) {
+	var from, to model.CIStr
+	if err := job.DecodeArgs(&from, &to); err != nil {
+		job.State = model.JobStateCancelled
+		return ver, errors.Trace(err)
+	}
+	tblInfo, err := getTableInfo(t, job, job.SchemaID)
+	if err != nil {
+		job.State = model.JobStateCancelled
+		return ver, errors.Trace(err)
+	}
+
+	// Double check. See function `RenameIndex` in ddl_api.go
+	duplicate, err := validateRenameIndex(from, to, tblInfo)
+	if duplicate {
+		return ver, nil
+	}
+	if err != nil {
+		job.State = model.JobStateCancelled
+		return ver, errors.Trace(err)
+	}
+	idx := findIndexByName(from.L, tblInfo.Indices)
+	idx.Name = to
+	if ver, err = updateVersionAndTableInfo(t, job, tblInfo, true); err != nil {
+		job.State = model.JobStateCancelled
+		return ver, errors.Trace(err)
+	}
+	job.FinishTableJob(model.JobStateDone, model.StatePublic, ver, tblInfo)
+	return ver, nil
+}
+
 func checkTableNotExists(t *meta.Meta, job *model.Job, schemaID int64, tableName string) error {
 	// Check this table's database.
 	tables, err := t.ListTables(schemaID)

infoschema/infoschema.go

@@ -50,6 +50,10 @@ var (
 	ErrColumnExists = terror.ClassSchema.New(codeColumnExists, "Duplicate column name '%s'")
 	// ErrIndexExists returns for index already exists.
 	ErrIndexExists = terror.ClassSchema.New(codeIndexExists, "Duplicate Index")
+	// ErrKeyNameDuplicate returns for index duplicate when rename index.
+	ErrKeyNameDuplicate = terror.ClassSchema.New(codeKeyNameDuplicate, "Duplicate key name '%s'")
+	// ErrKeyNotExists returns for index not exists.
+	ErrKeyNotExists = terror.ClassSchema.New(codeKeyNotExists, "Key '%s' doesn't exist in table '%s'")
 	// ErrMultiplePriKey returns for multiple primary keys.
 	ErrMultiplePriKey = terror.ClassSchema.New(codeMultiplePriKey, "Multiple primary key defined")
 	// ErrTooManyKeyParts returns for too many key parts.
@@ -279,13 +283,15 @@ const (
 	codeForeignKeyNotExists = 1091
 	codeWrongFkDef          = 1239
 
-	codeDatabaseExists  = 1007
-	codeTableExists     = 1050
-	codeBadTable        = 1051
-	codeColumnExists    = 1060
-	codeIndexExists     = 1831
-	codeMultiplePriKey  = 1068
-	codeTooManyKeyParts = 1070
+	codeDatabaseExists   = 1007
+	codeTableExists      = 1050
+	codeBadTable         = 1051
+	codeColumnExists     = 1060
+	codeIndexExists      = 1831
+	codeMultiplePriKey   = 1068
+	codeTooManyKeyParts  = 1070
+	codeKeyNameDuplicate = 1061
+	codeKeyNotExists     = 1176
 )
 
 func init() {
@@ -304,6 +310,8 @@ func init() {
 		codeIndexExists:         mysql.ErrDupIndex,
 		codeMultiplePriKey:      mysql.ErrMultiplePriKey,
 		codeTooManyKeyParts:     mysql.ErrTooManyKeyParts,
+		codeKeyNameDuplicate:    mysql.ErrDupKeyName,
+		codeKeyNotExists:        mysql.ErrKeyDoesNotExist,
 	}
 	terror.ErrClassToMySQLCodes[terror.ClassSchema] = schemaMySQLErrCodes
 	initInfoSchemaDB()

model/ddl.go

@@ -47,6 +47,7 @@ const (
 	ActionSetDefaultValue    ActionType = 15
 	ActionShardRowID         ActionType = 16
 	ActionModifyTableComment ActionType = 17
+	ActionRenameIndex        ActionType = 18
 )
 
 var actionMap = map[ActionType]string{
@@ -67,6 +68,7 @@ var actionMap = map[ActionType]string{
 	ActionSetDefaultValue:    "set default value",
 	ActionShardRowID:         "shard row ID",
 	ActionModifyTableComment: "modify table comment",
+	ActionRenameIndex:        "rename index",
 }
 
 // String return current ddl action in string

parser/parser.y

@@ -1040,6 +1040,14 @@ AlterTableSpec:
 			NewTable:      $3.(*ast.TableName),
 		}
 	}
+|	"RENAME" KeyOrIndex Identifier "TO" Identifier
+	{
+		$$ = &ast.AlterTableSpec{
+			Tp:    	    ast.AlterTableRenameIndex,
+			FromKey:    model.NewCIStr($3),
+			ToKey:      model.NewCIStr($5),
+		}
+	}
 |	LockClause
 	{
 		$$ = &ast.AlterTableSpec{

parser/parser_test.go

@@ -1632,6 +1632,9 @@ func (s *testParserSuite) TestDDL(c *C) {
 		{"ALTER TABLE t CONVERT TO CHARSET utf8 COLLATE utf8_bin;", true},
 		{"ALTER TABLE t FORCE", true},
 		{"ALTER TABLE t DROP INDEX;", false},
+		// For #6405
+		{"ALTER TABLE t RENAME KEY a TO b;", true},
+		{"ALTER TABLE t RENAME INDEX a TO b;", true},
 
 		// For create index statement
 		{"CREATE INDEX idx ON t (a)", true},