ddl: fix drop index failed when index contain auto_increment column a…

…nd the auto_increment column is primary key (#15861) (#16008)
pingcap · Apr 14, 2020 · 2da2351 · 2da2351
1 parent 31f87b8
commit 2da2351
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Showing 2 changed files with 13 additions and 1 deletion.
diff --git a/ddl/index.go b/ddl/index.go
@@ -592,7 +592,8 @@ func checkDropIndex(t *meta.Meta, job *model.Job) (*model.TableInfo, *model.Inde
 func checkDropIndexOnAutoIncrementColumn(tblInfo *model.TableInfo, indexInfo *model.IndexInfo) error {
 	cols := tblInfo.Columns
 	for _, idxCol := range indexInfo.Columns {
-		if !mysql.HasAutoIncrementFlag(cols[idxCol.Offset].Flag) {
+		flag := cols[idxCol.Offset].Flag
+		if !mysql.HasAutoIncrementFlag(flag) {
 			continue
 		}
 		// check the count of index on auto_increment column.
@@ -605,6 +606,9 @@ func checkDropIndexOnAutoIncrementColumn(tblInfo *model.TableInfo, indexInfo *mo
 				}
 			}
 		}
+		if tblInfo.PKIsHandle && mysql.HasPriKeyFlag(flag) {
+			count++
+		}
 		if count < 2 {
 			return autoid.ErrWrongAutoKey
 		}

diff --git a/ddl/serial_test.go b/ddl/serial_test.go
@@ -150,6 +150,14 @@ func (s *testSerialSuite) TestPrimaryKey(c *C) {
 	c.Assert(err.Error(), Equals, "[ddl:206]Unsupported drop primary key when alter-primary-key is false")
 }
 
+func (s *testSerialSuite) TestDropAutoIncrementIndex(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t1")
+	tk.MustExec("create table t1 (a int(11) not null auto_increment key, b int(11), c bigint, unique key (a, b, c))")
+	tk.MustExec("alter table t1 drop index a")
+}
+
 func (s *testSerialSuite) TestMultiRegionGetTableEndHandle(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("drop database if exists test_get_endhandle")