Prohibit change name of partitioning column

ddl/column_change_test.go

@@ -437,3 +437,27 @@ func testNewContext(store kv.Storage) sessionctx.Context {
 	ctx.Store = store
 	return ctx
 }
+
+func TestIssue40135(t *testing.T) {
+	store, dom := testkit.CreateMockStoreAndDomain(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+
+	tk1 := testkit.NewTestKit(t, store)
+	tk1.MustExec("use test")
+
+	tk.MustExec("CREATE TABLE t40135 ( a tinyint DEFAULT NULL, b varchar(32) DEFAULT 'md') PARTITION BY HASH (a) PARTITIONS 2")
+	one := true
+	hook := &ddl.TestDDLCallback{Do: dom}
+	var checkErr error
+	hook.OnJobRunBeforeExported = func(job *model.Job) {
+		if one {
+			one = false
+			_, checkErr = tk1.Exec("alter table t40135 change column a aNew SMALLINT NULL DEFAULT '-14996'")
+		}
+	}
+	dom.DDL().SetHook(hook)
+	tk.MustExec("alter table t40135 modify column a MEDIUMINT NULL DEFAULT '6243108' FIRST")
+
+	require.ErrorContains(t, checkErr, "[ddl:8200]Unsupported modify column: Column 'a' has a partitioning function dependency and cannot be renamed")
+}

ddl/ddl_api.go

@@ -4698,9 +4698,15 @@ func GetModifiableColumnJob(
 		for _, name := range pt.GetPartitionColumnNames() {
 			if strings.EqualFold(name.L, col.Name.L) {
 				isPartitioningColumn = true
+				break
 			}
 		}
 		if isPartitioningColumn {
+			// TODO: update the partitioning columns with new names if column is renamed
+			// Would be an extension from MySQL which does not support it.
+			if col.Name.L != newCol.Name.L {
+				return nil, dbterror.ErrUnsupportedModifyColumn.GenWithStackByArgs(fmt.Sprintf("Column '%s' has a partitioning function dependency and cannot be renamed", col.Name.O))
+			}
 			if !isColTypeAllowedAsPartitioningCol(newCol.FieldType) {
 				return nil, dbterror.ErrNotAllowedTypeInPartition.GenWithStackByArgs(newCol.Name.O)
 			}
@@ -4744,7 +4750,6 @@ func GetModifiableColumnJob(
 			newTblInfo.Columns = newCols
 
 			var buf bytes.Buffer
-			// TODO: update the partitioning columns with new names if column is renamed
 			AppendPartitionInfo(tblInfo.GetPartitionInfo(), &buf, mysql.ModeNone)
 			// The parser supports ALTER TABLE ... PARTITION BY ... even if the ddl code does not yet :)
 			// Ignoring warnings