ddl: fix cast date as timestamp will write invalid value (pingcap#26362)

ddl/column_type_change_test.go

@@ -2112,6 +2112,7 @@ func (s *testColumnTypeChangeSuite) TestCastToTimeStampDecodeError(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test;")
 
+	tk.MustExec("drop table if exists t")
 	tk.MustExec("CREATE TABLE `t` (" +
 		"  `a` datetime DEFAULT '1764-06-11 02:46:14'" +
 		") ENGINE=InnoDB DEFAULT CHARSET=latin1 COLLATE=latin1_bin COMMENT='7b84832e-f857-4116-8872-82fc9dcc4ab3'")
@@ -2129,3 +2130,52 @@ func (s *testColumnTypeChangeSuite) TestCastToTimeStampDecodeError(c *C) {
 	// Normal cast datetime to timestamp can succeed.
 	tk.MustQuery("select timestamp(cast('1000-11-11 12-3-1' as date));").Check(testkit.Rows("1000-11-11 00:00:00"))
 }
+
+// Fix issue: https://github.com/pingcap/tidb/issues/26292
+// Cast date to timestamp has two kind behavior: cast("3977-02-22" as date)
+// For select statement, it truncate the string and return no errors. (which is 3977-02-22 00:00:00 here)
+// For ddl reorging or changing column in ctc, it need report some errors.
+func (s *testColumnTypeChangeSuite) TestCastDateToTimestampInReorgAttribute(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test;")
+
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("CREATE TABLE `t` (`a` DATE NULL DEFAULT '8497-01-06')")
+	tk.MustExec("insert into t values(now())")
+
+	originalHook := s.dom.DDL().GetHook()
+	defer s.dom.DDL().(ddl.DDLForTest).SetHook(originalHook)
+
+	// use new session to check meta in callback function.
+	internalTK := testkit.NewTestKit(c, s.store)
+	internalTK.MustExec("use test")
+
+	tbl := testGetTableByName(c, tk.Se, "test", "t")
+	c.Assert(tbl, NotNil)
+	c.Assert(len(tbl.Cols()), Equals, 1)
+
+	hook := &ddl.TestDDLCallback{}
+	var (
+		checkErr1 error
+		checkErr2 error
+	)
+	hook.OnJobRunBeforeExported = func(job *model.Job) {
+		if checkErr1 != nil || checkErr2 != nil {
+			return
+		}
+		if tbl.Meta().ID != job.TableID {
+			return
+		}
+		switch job.SchemaState {
+		case model.StateWriteOnly:
+			_, checkErr1 = internalTK.Exec("insert into `t` set  `a` = '3977-02-22'") // this(string) will be cast to a as date, then cast a(date) as timestamp to changing column.
+			_, checkErr2 = internalTK.Exec("update t set `a` = '3977-02-22'")
+		}
+	}
+	s.dom.DDL().(ddl.DDLForTest).SetHook(hook)
+
+	tk.MustExec("alter table t modify column a  TIMESTAMP NULL DEFAULT '2021-04-28 03:35:11' FIRST")
+	c.Assert(checkErr1.Error(), Equals, "[types:1292]Incorrect datetime value: '3977-02-22 00:00:00'")
+	c.Assert(checkErr2.Error(), Equals, "[types:1292]Incorrect datetime value: '3977-02-22 00:00:00'")
+	tk.MustExec("drop table if exists t")
+}

sessionctx/stmtctx/stmtctx.go

@@ -63,7 +63,9 @@ type StatementContext struct {
 
 	// IsDDLJobInQueue is used to mark whether the DDL job is put into the queue.
 	// If IsDDLJobInQueue is true, it means the DDL job is in the queue of storage, and it can be handled by the DDL worker.
-	IsDDLJobInQueue           bool
+	IsDDLJobInQueue bool
+	// InReorgAttribute is indicated for cast function that the transition is a kind of reorg process.
+	InReorgAttribute          bool
 	InInsertStmt              bool
 	InUpdateStmt              bool
 	InDeleteStmt              bool

table/column.go

@@ -248,6 +248,14 @@ func handleZeroDatetime(ctx sessionctx.Context, col *model.ColumnInfo, casted ty
 // TODO: change the third arg to TypeField. Not pass ColumnInfo.
 func CastValue(ctx sessionctx.Context, val types.Datum, col *model.ColumnInfo, returnErr, forceIgnoreTruncate bool) (casted types.Datum, err error) {
 	sc := ctx.GetSessionVars().StmtCtx
+	// Set the reorg attribute for cast value functionality.
+	if col.ChangeStateInfo != nil {
+		origin := ctx.GetSessionVars().StmtCtx.InReorgAttribute
+		ctx.GetSessionVars().StmtCtx.InReorgAttribute = true
+		defer func() {
+			ctx.GetSessionVars().StmtCtx.InReorgAttribute = origin
+		}()
+	}
 	casted, err = val.ConvertTo(sc, &col.FieldType)
 	// TODO: make sure all truncate errors are handled by ConvertTo.
 	if returnErr && err != nil {

types/datum.go

@@ -1130,7 +1130,7 @@ func (d *Datum) convertToMysqlTimestamp(sc *stmtctx.StatementContext, target *Fi
 	case KindMysqlTime:
 		// `select timestamp(cast("1000-01-02 23:59:59" as date)); ` casts usage will succeed.
 		// Alter datetime("1000-01-02 23:59:59") to timestamp will error.
-		if sc.IsDDLJobInQueue {
+		if sc.InReorgAttribute {
 			t, err = d.GetMysqlTime().Convert(sc, target.Tp)
 			if err != nil {
 				ret.SetMysqlTime(t)