diff --git a/source/libs/parser/src/parCalcConst.c b/source/libs/parser/src/parCalcConst.c
index c25d0e7036..01b62a9051 100644
--- a/source/libs/parser/src/parCalcConst.c
+++ b/source/libs/parser/src/parCalcConst.c
@@ -388,6 +388,9 @@ static bool isSetUselessCol(SSetOperator* pSetOp, int32_t index, SExprNode* pPro
 }
 
 static int32_t calcConstSetOpProjections(SCalcConstContext* pCxt, SSetOperator* pSetOp, bool subquery) {
+  if (subquery && pSetOp->opType == SET_OP_TYPE_UNION) {
+    return TSDB_CODE_SUCCESS;
+  }
   int32_t index = 0;
   SNode*  pProj = NULL;
   WHERE_EACH(pProj, pSetOp->pProjectionList) {
diff --git a/source/libs/planner/src/planner.c b/source/libs/planner/src/planner.c
index c6a4a97f6e..58b8e53478 100644
--- a/source/libs/planner/src/planner.c
+++ b/source/libs/planner/src/planner.c
@@ -19,6 +19,14 @@
 #include "scalar.h"
 #include "tglobal.h"
 
+static void debugPrintNode(SNode* pNode) {
+  char* pStr = NULL;
+  nodesNodeToString(pNode, false, &pStr, NULL);
+  printf("%s\n", pStr);
+  taosMemoryFree(pStr);
+  return;
+}
+
 static void dumpQueryPlan(SQueryPlan* pPlan) {
   if (!tsQueryPlannerTrace) {
     return;
diff --git a/tests/script/tsim/query/unionall_as_table.sim b/tests/script/tsim/query/unionall_as_table.sim
index dc3d2cbec4..4d8f990718 100644
--- a/tests/script/tsim/query/unionall_as_table.sim
+++ b/tests/script/tsim/query/unionall_as_table.sim
@@ -25,4 +25,21 @@ if $data05 != @0021001@ then
   return -1
 endi
 
+sql create table st (ts timestamp, f int) tags (t int);
+sql insert into ct1 using st tags(1) values(now, 1)(now+1s, 2)
+sql insert into ct2 using st tags(2) values(now+2s, 3)(now+3s, 4)
+sql select count(*) from (select * from ct1 union all select * from ct2)
+if $rows != 1 then
+  return -1
+endi
+if $data00 != 4 then
+  return -1
+endi
+sql select count(*) from (select * from ct1 union select * from ct2)
+if $rows != 1 then
+  return -1
+endi
+if $data00 != 4 then
+  return -1
+endi
 system sh/exec.sh -n dnode1 -s stop -x SIGINT