session: do not allow historical read in local temporary tables (#27363)

ddl/db_integration_test.go

@@ -2951,10 +2951,6 @@ func (s *testIntegrationSuite3) TestCreateTemporaryTable(c *C) {
 	ON DUPLICATE KEY
 	UPDATE variable_value = '%[2]s', comment = '%[3]s'`, safePointName, safePointValue, safePointComment)
 	tk.MustExec(updateSafePoint)
-
-	// Considering snapshot, local temporary table is always visible.
-	tk.MustExec("set @@tidb_snapshot = '2016-01-01 15:04:05.999999'")
-	tk.MustExec("select * from overlap")
 }
 
 func (s *testIntegrationSuite3) TestAvoidCreateViewOnLocalTemporaryTable(c *C) {

executor/builder.go

@@ -4525,6 +4525,10 @@ func (b *executorBuilder) validCanReadTemporaryTable(tbl *model.TableInfo) error
 
 	sessionVars := b.ctx.GetSessionVars()
 
+	if tbl.TempTableType == model.TempTableLocal && sessionVars.SnapshotTS != 0 {
+		return errors.New("can not read local temporary table when 'tidb_snapshot' is set")
+	}
+
 	if sessionVars.TxnCtx.IsStaleness || b.isStaleness {
 		return errors.New("can not stale read temporary table")
 	}

executor/executor_test.go

@@ -8955,9 +8955,13 @@ func (s *testStaleTxnSuite) TestInvalidReadTemporaryTable(c *C) {
 
 	tk.MustExec("set @@tidb_snapshot=NOW(6)")
 	for _, query := range queries {
+		// forbidden historical read local temporary table
+		if strings.Contains(query.sql, "tmp2") {
+			tk.MustGetErrMsg(query.sql, "can not read local temporary table when 'tidb_snapshot' is set")
+			continue
+		}
 		// Will success here for compatibility with some tools like dumping
-		rs := tk.MustQuery(query.sql)
-		rs.Check(testkit.Rows())
+		tk.MustQuery(query.sql).Check(testkit.Rows())
 	}
 }