ddl: improve priority of suppressErrorTooLongKeyKey for DM (#55164)

close #55138

pkg/ddl/index.go

@@ -88,7 +88,10 @@ var (
 	SuppressErrorTooLongKeyKey stringutil.StringerStr = "suppressErrorTooLongKeyKey"
 )
 
-func suppressErrorTooLongKeyKey(sctx sessionctx.Context) bool {
+func suppressErrorTooLongKeyForSchemaTracker(sctx sessionctx.Context) bool {
+	if sctx == nil {
+		return false
+	}
 	if suppress, ok := sctx.Value(SuppressErrorTooLongKeyKey).(bool); ok && suppress {
 		return true
 	}
@@ -130,11 +133,12 @@ func buildIndexColumns(ctx sessionctx.Context, columns []*model.ColumnInfo, inde
 		}
 		sumLength += indexColumnLength
 
-		// The sum of all lengths must be shorter than the max length for prefix.
-		if sumLength > maxIndexLength {
+		if !suppressErrorTooLongKeyForSchemaTracker(ctx) && sumLength > maxIndexLength {
+			// The sum of all lengths must be shorter than the max length for prefix.
+
 			// The multiple column index and the unique index in which the length sum exceeds the maximum size
 			// will return an error instead produce a warning.
-			if ctx == nil || (ctx.GetSessionVars().SQLMode.HasStrictMode() && !suppressErrorTooLongKeyKey(ctx)) || mysql.HasUniKeyFlag(col.GetFlag()) || len(indexPartSpecifications) > 1 {
+			if ctx == nil || ctx.GetSessionVars().SQLMode.HasStrictMode() || mysql.HasUniKeyFlag(col.GetFlag()) || len(indexPartSpecifications) > 1 {
 				return nil, false, dbterror.ErrTooLongKey.GenWithStackByArgs(sumLength, maxIndexLength)
 			}
 			// truncate index length and produce warning message in non-restrict sql mode.
@@ -261,7 +265,7 @@ func checkIndexColumn(ctx sessionctx.Context, col *model.ColumnInfo, indexColumn
 	// Specified length must be shorter than the max length for prefix.
 	maxIndexLength := config.GetGlobalConfig().MaxIndexLength
 	if indexColumnLen > maxIndexLength {
-		if ctx == nil || (ctx.GetSessionVars().SQLMode.HasStrictMode() && !suppressErrorTooLongKeyKey(ctx)) {
+		if ctx == nil || (ctx.GetSessionVars().SQLMode.HasStrictMode() && !suppressErrorTooLongKeyForSchemaTracker(ctx)) {
 			// return error in strict sql mode
 			return dbterror.ErrTooLongKey.GenWithStackByArgs(indexColumnLen, maxIndexLength)
 		}

pkg/ddl/schematracker/dm_tracker.go

@@ -38,11 +38,14 @@ import (
 	"github.com/pingcap/tidb/pkg/util/dbterror"
 )
 
-// SchemaTracker is used to track schema changes by DM. It implements DDL interface and by applying DDL, it updates the
-// table structure to keep tracked with upstream changes.
-// It embeds an InfoStore which stores DBInfo and TableInfo. The DBInfo and TableInfo can be treated as immutable, so
-// after reading them by SchemaByName or TableByName, later modifications made by SchemaTracker will not change them.
-// SchemaTracker is not thread-safe.
+// SchemaTracker is used to track schema changes by DM. It implements
+// ddl.Executor interface and by applying DDL, it updates the table structure to
+// keep tracked with upstream changes.
+//
+// It embeds an InfoStore which stores DBInfo and TableInfo. The DBInfo and
+// TableInfo can be treated as immutable, so after reading them by SchemaByName
+// or TableByName, later modifications made by SchemaTracker will not change
+// them. SchemaTracker is not thread-safe.
 type SchemaTracker struct {
 	*InfoStore
 }

pkg/ddl/schematracker/dm_tracker_test.go

@@ -86,6 +86,10 @@ func TestCreateTableLongIndex(t *testing.T) {
 	tracker := schematracker.NewSchemaTracker(2)
 	tracker.CreateTestDB(nil)
 	execCreate(t, tracker, sql)
+	sql2 := "create table test.t2 (c1 int, c2 blob, c3 varchar(64), unique index idx_c2(c2(555555)));"
+	execCreate(t, tracker, sql2)
+	sql3 := "create table test.t3 (c1 int, c2 blob, c3 varchar(64), index idx_c2_c3(c3, c2(555555)));"
+	execCreate(t, tracker, sql3)
 }
 
 func execAlter(t *testing.T, tracker schematracker.SchemaTracker, sql string) {