planner: fix incompatible behaviors between prep and non-prep stateme…

…nts when converting date/time values (#42443) (#46710)

close #42439

planner/core/prepare_test.go

@@ -1534,6 +1534,19 @@ func TestIssue33067(t *testing.T) {
 	tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("0"))
 }
 
+func TestIssue42439(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec(`use test`)
+	tk.MustExec(`CREATE TABLE UK_MU16407 (COL3 timestamp NULL DEFAULT NULL, UNIQUE KEY U3(COL3))`)
+	tk.MustExec(`insert into UK_MU16407 values("1985-08-31 18:03:27")`)
+	tk.MustExec(`PREPARE st FROM 'SELECT COL3 FROM UK_MU16407 WHERE COL3>?'`)
+	tk.MustExec(`set @a='2039-1-19 3:14:40'`)
+	tk.MustExec(`execute st using @a`) // no error
+	tk.MustExec(`set @a='1950-1-19 3:14:40'`)
+	tk.MustQuery(`execute st using @a`).Check(testkit.Rows(`1985-08-31 18:03:27`))
+}
+
 func TestIssue29486(t *testing.T) {
 	store := testkit.CreateMockStore(t)
 	tk := testkit.NewTestKit(t, store)

util/ranger/ranger.go

@@ -161,8 +161,8 @@ func convertPoint(sctx sessionctx.Context, point *point, tp *types.FieldType) (*
 	casted, err := point.value.ConvertTo(sc, tp)
 	if err != nil {
 		if sctx.GetSessionVars().StmtCtx.InPreparedPlanBuilding {
-			// do not ignore these errors if in prepared plan building for safety
-			return nil, errors.Trace(err)
+			// skip plan cache in this case for safety.
+			sctx.GetSessionVars().StmtCtx.SetSkipPlanCache(errors.Errorf("%s when converting %v", err.Error(), point.value))
 		}
 		//revive:disable:empty-block
 		if tp.GetType() == mysql.TypeYear && terror.ErrorEqual(err, types.ErrWarnDataOutOfRange) {