executor: check schema when build table reader executor (#50425) (#50561

)

ref #50358

executor/builder.go

@@ -3466,6 +3466,10 @@ func (b *executorBuilder) buildTableReader(v *plannercore.PhysicalTableReader) E
 			failpoint.Return(nil)
 		}
 	})
+	// https://github.com/pingcap/tidb/issues/50358
+	if len(v.Schema().Columns) == 0 && len(v.GetTablePlan().Schema().Columns) > 0 {
+		v.SetSchema(v.GetTablePlan().Schema())
+	}
 	if useMPPExecution(b.ctx, v) {
 		return b.buildMPPGather(v)
 	}

executor/tiflashtest/tiflash_test.go

@@ -1348,3 +1348,32 @@ func TestMPPMemoryTracker(t *testing.T) {
 	require.NotNil(t, err)
 	require.True(t, strings.Contains(err.Error(), memory.PanicMemoryExceedWarnMsg+memory.WarnMsgSuffixForSingleQuery))
 }
+
+func TestIssue50358(t *testing.T) {
+	store := testkit.CreateMockStore(t, withMockTiFlash(1))
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t(a int not null primary key, b int not null)")
+	tk.MustExec("alter table t set tiflash replica 1")
+	tb := external.GetTableByName(t, tk, "test", "t")
+	err := domain.GetDomain(tk.Session()).DDL().UpdateTableReplicaInfo(tk.Session(), tb.Meta().ID, true)
+	require.NoError(t, err)
+	tk.MustExec("insert into t values(1,0)")
+	tk.MustExec("insert into t values(2,0)")
+
+	tk.MustExec("drop table if exists t1")
+	tk.MustExec("create table t1(c int not null primary key)")
+	tk.MustExec("alter table t1 set tiflash replica 1")
+	tb = external.GetTableByName(t, tk, "test", "t1")
+	err = domain.GetDomain(tk.Session()).DDL().UpdateTableReplicaInfo(tk.Session(), tb.Meta().ID, true)
+	require.NoError(t, err)
+	tk.MustExec("insert into t1 values(3)")
+
+	tk.MustExec("set @@session.tidb_isolation_read_engines=\"tiflash\"")
+	tk.MustExec("set @@session.tidb_allow_mpp=ON")
+	for i := 0; i < 20; i++ {
+		// test if it is stable.
+		tk.MustQuery("select 8 from t join t1").Check(testkit.Rows("8", "8"))
+	}
+}