planner, expression: fix a bug causes schema change after DML (#21027) (

#21050) Signed-off-by: ti-srebot <ti-srebot@pingcap.com>
pingcap · Nov 17, 2020 · 1e4def5 · 1e4def5
1 parent a1bdbef
commit 1e4def5
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Showing 4 changed files with 17 additions and 3 deletions.
diff --git a/expression/expression.go b/expression/expression.go
@@ -779,7 +779,7 @@ func ColumnInfos2ColumnsAndNames(ctx sessionctx.Context, dbName, tblName model.C
 			ColName:     col.Name,
 		})
 		newCol := &Column{
-			RetType:  &col.FieldType,
+			RetType:  col.FieldType.Clone(),
 			ID:       col.ID,
 			UniqueID: ctx.GetSessionVars().AllocPlanColumnID(),
 			Index:    col.Offset,

diff --git a/expression/integration_test.go b/expression/integration_test.go
@@ -6777,6 +6777,20 @@ func (s *testIntegrationSerialSuite) TestIssue17989(c *C) {
 	tk.MustExec("admin check table t")
 }
 
+func (s *testIntegrationSuite2) TestSchemaDMLNotChange(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk2 := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk2.MustExec("use test")
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t (id int primary key, c_json json);")
+	tk.MustExec("insert into t values (1, '{\"k\": 1}');")
+	tk.MustExec("begin")
+	tk.MustExec("update t set c_json = '{\"k\": 2}' where id = 1;")
+	tk2.MustExec("alter table t rename column c_json to cc_json;")
+	tk.MustExec("commit")
+}
+
 func (s *testIntegrationSerialSuite) TestIssue18702(c *C) {
 	collate.SetNewCollationEnabledForTest(true)
 	defer collate.SetNewCollationEnabledForTest(false)

diff --git a/planner/core/logical_plan_builder.go b/planner/core/logical_plan_builder.go
@@ -2948,7 +2948,7 @@ func (b *PlanBuilder) buildDataSource(ctx context.Context, tn *ast.TableName, as
 		newCol := &expression.Column{
 			UniqueID: sessionVars.AllocPlanColumnID(),
 			ID:       col.ID,
-			RetType:  &col.FieldType,
+			RetType:  col.FieldType.Clone(),
 			OrigName: names[i].String(),
 			IsHidden: col.Hidden,
 		}

diff --git a/planner/core/point_get_plan.go b/planner/core/point_get_plan.go
@@ -1172,7 +1172,7 @@ func findCol(tbl *model.TableInfo, colName *ast.ColumnName) *model.ColumnInfo {
 
 func colInfoToColumn(col *model.ColumnInfo, idx int) *expression.Column {
 	return &expression.Column{
-		RetType:  &col.FieldType,
+		RetType:  col.FieldType.Clone(),
 		ID:       col.ID,
 		UniqueID: int64(col.Offset),
 		Index:    idx,