*: fix parallel execution "alter index" (cherry-pick pingcap#45582 and fixed "alter index" issue) (pingcap#45584)

close pingcap#45575

Author: zimulala

ddl/db_change_test.go

@@ -946,6 +946,16 @@ func (s *stateChangeSuite) TestShowIndex() {
 	tk.MustQuery("select key_name, clustered from information_schema.tidb_indexes where table_name = 'tr' order by key_name").Check(testkit.Rows("PRIMARY NO", "vv NO"))
 }
 
+func (s *stateChangeSuite) TestParallelAlterIndex() {
+	sql := "alter table t alter index idx1 invisible;"
+	f := func(err1, err2 error) {
+		s.Require().NoError(err1)
+		s.Require().NoError(err2)
+		s.tk.MustExec("select * from t")
+	}
+	s.testControlParallelExecSQL("", sql, sql, f)
+}
+
 func (s *stateChangeSuite) TestParallelAlterModifyColumn() {
 	sql := "ALTER TABLE t MODIFY COLUMN b int FIRST;"
 	f := func(err1, err2 error) {

ddl/index.go

@@ -1002,6 +1002,7 @@ func checkAlterIndexVisibility(t *meta.Meta, job *model.Job) (*model.TableInfo,
 		return nil, indexName, invisible, errors.Trace(err)
 	}
 	if skip {
+		job.State = model.JobStateDone
 		return nil, indexName, invisible, nil
 	}
 	return tblInfo, indexName, invisible, nil