table: fix cannot find the temp table when it's created in a transact…

…ion (#35663)

close #35644

ddl/db_integration_test.go

@@ -3814,6 +3814,26 @@ func TestIssue29282(t *testing.T) {
 	}
 }
 
+// See https://github.com/pingcap/tidb/issues/35644
+func TestCreateTempTableInTxn(t *testing.T) {
+	store, clean := testkit.CreateMockStore(t)
+	defer clean()
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("begin")
+	tk.MustExec("create temporary table t1(id int)")
+	tk.MustQuery("select * from t1")
+	tk.MustExec("commit")
+
+	tk1 := testkit.NewTestKit(t, store)
+	tk1.MustExec("use test")
+	tk1.MustExec("create table tt(id int)")
+	tk1.MustExec("begin")
+	tk1.MustExec("create temporary table t1(id int)")
+	tk1.MustExec("insert into tt select * from t1")
+	tk1.MustExec("drop table tt")
+}
+
 // See https://github.com/pingcap/tidb/issues/29327
 func TestEnumDefaultValue(t *testing.T) {
 	store, clean := testkit.CreateMockStore(t)

infoschema/infoschema.go

@@ -487,6 +487,11 @@ func (is *LocalTemporaryTables) RemoveTable(schema, table model.CIStr) (exist bo
 	return true
 }
 
+// Count gets the count of the temporary tables.
+func (is *LocalTemporaryTables) Count() int {
+	return len(is.idx2table)
+}
+
 // SchemaByTable get a table's schema name
 func (is *LocalTemporaryTables) SchemaByTable(tableInfo *model.TableInfo) (*model.DBInfo, bool) {
 	if tableInfo == nil {

table/temptable/ddl_test.go

@@ -164,7 +164,7 @@ func TestTruncateLocalTemporaryTable(t *testing.T) {
 	// truncate when empty
 	err := ddl.TruncateLocalTemporaryTable(model.NewCIStr("db1"), model.NewCIStr("t1"))
 	require.True(t, infoschema.ErrTableNotExists.Equal(err))
-	require.Nil(t, sessVars.LocalTemporaryTables)
+	require.Equal(t, 0, sessVars.LocalTemporaryTables.(*infoschema.LocalTemporaryTables).Count())
 	require.Nil(t, sessVars.TemporaryTableData)
 
 	// add one table

table/temptable/infoschema.go

@@ -26,10 +26,6 @@ func AttachLocalTemporaryTableInfoSchema(sctx sessionctx.Context, is infoschema.
 	}
 
 	localTemporaryTables := getLocalTemporaryTables(sctx)
-	if localTemporaryTables == nil {
-		return is
-	}
-
 	return &infoschema.TemporaryTableAttachedInfoSchema{
 		InfoSchema:           is,
 		LocalTemporaryTables: localTemporaryTables,
@@ -46,12 +42,8 @@ func DetachLocalTemporaryTableInfoSchema(is infoschema.InfoSchema) infoschema.In
 }
 
 func getLocalTemporaryTables(sctx sessionctx.Context) *infoschema.LocalTemporaryTables {
-	localTemporaryTables := sctx.GetSessionVars().LocalTemporaryTables
-	if localTemporaryTables == nil {
-		return nil
-	}
-
-	return localTemporaryTables.(*infoschema.LocalTemporaryTables)
+	// Do not return nil so that new created tables can always be visited through the returned object.
+	return ensureLocalTemporaryTables(sctx)
 }
 
 func ensureLocalTemporaryTables(sctx sessionctx.Context) *infoschema.LocalTemporaryTables {