diff --git a/source/libs/function/src/texpr.c b/source/libs/function/src/texpr.c
index 6970b85638..70a7e9973f 100644
--- a/source/libs/function/src/texpr.c
+++ b/source/libs/function/src/texpr.c
@@ -13,6 +13,7 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "function.h"
 #include "os.h"
 
 #include "exception.h"
@@ -550,6 +551,15 @@ tExprNode* exprdup(tExprNode* pNode) {
   } else if (pNode->nodeType == TEXPR_COL_NODE) {
     pCloned->pSchema = calloc(1, sizeof(SSchema));
     *pCloned->pSchema = *pNode->pSchema;
+  } else if (pNode->nodeType == TEXPR_FUNCTION_NODE) {
+    strcpy(pCloned->_function.functionName, pNode->_function.functionName);
+
+    int32_t num = pNode->_function.num;
+    pCloned->_function.num = num;
+    pCloned->_function.pChild = calloc(num, POINTER_BYTES);
+    for(int32_t i = 0; i < num; ++i) {
+      pCloned->_function.pChild[i] = exprdup(pNode->_function.pChild[i]);
+    }
   }
 
   pCloned->nodeType = pNode->nodeType;
diff --git a/source/libs/parser/src/astGenerator.c b/source/libs/parser/src/astGenerator.c
index 53d05c87b3..f328486556 100644
--- a/source/libs/parser/src/astGenerator.c
+++ b/source/libs/parser/src/astGenerator.c
@@ -59,8 +59,7 @@ SArray *tListItemAppendToken(SArray *pList, SToken *pAliasToken, uint8_t sortOrd
 
   if (pAliasToken) {
     SListItem item;
-    assert(0);
-//    taosVariantCreate(&item.pVar, pAliasToken);
+    taosVariantCreate(&item.pVar, pAliasToken->z, pAliasToken->n, pAliasToken->type);
     item.sortOrder = sortOrder;
 
     taosArrayPush(pList, &item);
diff --git a/source/libs/parser/src/astValidate.c b/source/libs/parser/src/astValidate.c
index d9fd822b9b..7b6c423fb6 100644
--- a/source/libs/parser/src/astValidate.c
+++ b/source/libs/parser/src/astValidate.c
@@ -954,22 +954,32 @@ int32_t validateOrderbyNode(SQueryStmtInfo *pQueryInfo, SSqlNode* pSqlNode, SMsg
   }
 
   // handle the first part of order by
+  bool found = false;
   for(int32_t i = 0; i < taosArrayGetSize(pSortOrder); ++i) {
-    SVariant* pVar = taosArrayGet(pSortOrder, i);
+    SListItem* pItem = taosArrayGet(pSortOrder, i);
+
+    SVariant* pVar = &pItem->pVar;
     if (pVar->nType == TSDB_DATA_TYPE_BINARY) {
-      SColumn c = {0};
+      SOrder order = {0};
 
       // find the orde column among the result field.
       for (int32_t j = 0; j < getNumOfFields(&pQueryInfo->fieldsInfo); ++j) {
         SInternalField* pInfo = taosArrayGet(pQueryInfo->fieldsInfo.internalField, j);
         SSchema* pSchema = &pInfo->pExpr->base.resSchema;
         if (strcasecmp(pVar->pz, pSchema->name) == 0) {
-          setColumn(&c, pTableMetaInfo->pTableMeta->uid, pTableMetaInfo->aliasName, TSDB_COL_TMP, &pSchema);
-          return TSDB_CODE_SUCCESS;
+          setColumn(&order.col, pTableMetaInfo->pTableMeta->uid, pTableMetaInfo->aliasName, TSDB_COL_TMP, pSchema);
+
+          order.order = pItem->sortOrder;
+          taosArrayPush(pQueryInfo->order, &order);
+          found = true;
+          break;
         }
       }
 
-      return buildInvalidOperationMsg(pMsgBuf, "invalid order by column");
+      if (!found) {
+        return buildInvalidOperationMsg(pMsgBuf, "invalid order by column");
+      }
+
     } else {  // order by [1|2|3]
       if (pVar->i > getNumOfFields(&pQueryInfo->fieldsInfo)) {
         return buildInvalidOperationMsg(pMsgBuf, msg4);
@@ -980,6 +990,7 @@ int32_t validateOrderbyNode(SQueryStmtInfo *pQueryInfo, SSqlNode* pSqlNode, SMsg
 
       SOrder c = {0};
       setColumn(&c.col, pTableMetaInfo->pTableMeta->uid, pTableMetaInfo->aliasName, TSDB_COL_TMP, &pExprInfo->base.resSchema);
+      c.order = pItem->sortOrder;
       taosArrayPush(pQueryInfo->order, &c);
     }
   }
@@ -1248,16 +1259,17 @@ int32_t checkForInvalidOrderby(SQueryStmtInfo *pQueryInfo, SSqlNode* pSqlNode, S
 #endif
 
 static int32_t checkFillQueryRange(SQueryStmtInfo* pQueryInfo, SMsgBuf* pMsgBuf) {
-  const char* msg3 = "start(end) time of time range required or time range too large";
+  const char* msg1 = "start(end) time of time range required or time range too large";
 
   if (pQueryInfo->interval.interval == 0) {
     return TSDB_CODE_SUCCESS;
   }
 
-  bool initialWindows = TSWINDOW_IS_EQUAL(pQueryInfo->window, TSWINDOW_INITIALIZER);
-  if (initialWindows) {
-    return buildInvalidOperationMsg(pMsgBuf, msg3);
-  }
+  // TODO disable this check temporarily
+//  bool initialWindows = TSWINDOW_IS_EQUAL(pQueryInfo->window, TSWINDOW_INITIALIZER);
+//  if (initialWindows) {
+//    return buildInvalidOperationMsg(pMsgBuf, msg1);
+//  }
 
   int64_t timeRange = ABS(pQueryInfo->window.skey - pQueryInfo->window.ekey);
 
@@ -1267,7 +1279,7 @@ static int32_t checkFillQueryRange(SQueryStmtInfo* pQueryInfo, SMsgBuf* pMsgBuf)
 
     // number of result is not greater than 10,000,000
     if ((timeRange == 0) || (timeRange / intervalRange) >= MAX_INTERVAL_TIME_WINDOW) {
-      return buildInvalidOperationMsg(pMsgBuf, msg3);
+      return buildInvalidOperationMsg(pMsgBuf, msg1);
     }
   }
 
@@ -1384,7 +1396,8 @@ int32_t validateFillNode(SQueryStmtInfo *pQueryInfo, SSqlNode* pSqlNode, SMsgBuf
   return TSDB_CODE_SUCCESS;
 }
 
-static void exprInfoPushDown(SQueryStmtInfo* pQueryInfo);
+static void pushDownAggFuncExprInfo(SQueryStmtInfo* pQueryInfo);
+static void addColumnNodeFromLowerLevel(SQueryStmtInfo* pQueryInfo);
 
 int32_t validateSqlNode(SSqlNode* pSqlNode, SQueryStmtInfo* pQueryInfo, SMsgBuf* pMsgBuf) {
   assert(pSqlNode != NULL && (pSqlNode->from == NULL || taosArrayGetSize(pSqlNode->from->list) > 0));
@@ -1575,7 +1588,8 @@ int32_t validateSqlNode(SSqlNode* pSqlNode, SQueryStmtInfo* pQueryInfo, SMsgBuf*
     }
   }
 
-  exprInfoPushDown(pQueryInfo);
+  pushDownAggFuncExprInfo(pQueryInfo);
+//  addColumnNodeFromLowerLevel(pQueryInfo);
 
   for(int32_t i = 0; i < 1; ++i) {
     SArray* functionList = extractFunctionList(pQueryInfo->exprList[i]);
@@ -1629,15 +1643,29 @@ static bool isAllAggExpr(SArray* pList) {
   return true;
 }
 
-static SExprInfo* doCreateColumnNodeFromAggFunc(SSchema* pSchema);
+static bool isAllProjectExpr(SArray *pList) {
+  assert(pList != NULL);
 
-static void exprInfoPushDown(SQueryStmtInfo* pQueryInfo) {
+  for(int32_t i = 0; i < taosArrayGetSize(pList); ++i) {
+    SExprInfo* p = taosArrayGetP(pList, i);
+    if (p->pExpr->nodeType == TEXPR_FUNCTION_NODE && !qIsAggregateFunction(p->pExpr->_function.functionName)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+static SExprInfo* createColumnNodeFromAggFunc(SSchema* pSchema);
+
+static void pushDownAggFuncExprInfo(SQueryStmtInfo* pQueryInfo) {
   assert(pQueryInfo != NULL);
 
   size_t level = getExprFunctionLevel(pQueryInfo);
   for(int32_t i = 0; i < level - 1; ++i) {
     SArray* p = pQueryInfo->exprList[i];
 
+    // If direct lower level expressions are all aggregate function, check if current function can be push down or not
     SArray* pNext = pQueryInfo->exprList[i + 1];
     if (!isAllAggExpr(pNext)) {
       continue;
@@ -1650,8 +1678,8 @@ static void exprInfoPushDown(SQueryStmtInfo* pQueryInfo) {
         bool canPushDown = true;
         for (int32_t k = 0; k < taosArrayGetSize(pNext); ++k) {
           SExprInfo* pNextLevelExpr = taosArrayGetP(pNext, k);
+          // pExpr depends on the output of the down level, so it can not be push downwards
           if (pExpr->base.pColumns->info.colId == pNextLevelExpr->base.resSchema.colId) {
-            // pExpr is dependent on the output of the under layer, so it can not be push downwards
             canPushDown = false;
             break;
           }
@@ -1661,8 +1689,8 @@ static void exprInfoPushDown(SQueryStmtInfo* pQueryInfo) {
           taosArrayInsert(pNext, j, &pExpr);
           taosArrayRemove(p, j);
 
-          // todo add the project function in level of "i"
-          SExprInfo* pNew = doCreateColumnNodeFromAggFunc(&pExpr->base.resSchema);
+          // Add the project function of the current level, to output the calculated result
+          SExprInfo* pNew = createColumnNodeFromAggFunc(&pExpr->base.resSchema);
           taosArrayInsert(p, j, &pNew);
         }
       }
@@ -1670,6 +1698,49 @@ static void exprInfoPushDown(SQueryStmtInfo* pQueryInfo) {
   }
 }
 
+// todo change the logic plan data
+static void addColumnNodeFromLowerLevel(SQueryStmtInfo* pQueryInfo) {
+  assert(pQueryInfo != NULL);
+
+  size_t level = getExprFunctionLevel(pQueryInfo);
+  for (int32_t i = 0; i < level - 1; ++i) {
+    SArray* p = pQueryInfo->exprList[i];
+    if (isAllAggExpr(p)) {
+      continue;
+    }
+
+    // If direct lower level expressions are all aggregate function, check if current function can be push down or not
+    SArray* pNext = pQueryInfo->exprList[i + 1];
+    if (isAllAggExpr(pNext)) {
+      continue;
+    }
+
+    for (int32_t j = 0; j < taosArrayGetSize(pNext); ++j) {
+      SExprInfo* pExpr = taosArrayGetP(p, j);
+
+      bool exists = false;
+      for (int32_t k = 0; k < taosArrayGetSize(p); ++k) {
+        SExprInfo* pNextLevelExpr = taosArrayGetP(pNext, k);
+        // pExpr depends on the output of the down level, so it can not be push downwards
+        if (pExpr->base.pColumns->info.colId == pNextLevelExpr->base.resSchema.colId) {
+          exists = true;
+          break;
+        }
+      }
+
+      if (!exists) {
+        SExprInfo* pNew = calloc(1, sizeof(SExprInfo));
+        pNew->pExpr = exprdup(pExpr->pExpr);
+        memcpy(&pNew->base, &pExpr->base, sizeof(SSqlExpr));
+
+        int32_t pos = taosArrayGetSize(p);
+        // Add the project function of the current level, to output the calculated result
+        taosArrayInsert(p, pos - 1, &pExpr);
+      }
+    }
+  }
+}
+
 int32_t checkForInvalidExpr(SQueryStmtInfo* pQueryInfo, SMsgBuf* pMsgBuf) {
   assert(pQueryInfo != NULL && pMsgBuf != NULL);
 
@@ -3096,7 +3167,7 @@ static tExprNode* doCreateColumnNode(SQueryStmtInfo* pQueryInfo, SColumnIndex* p
   return pExpr;
 }
 
-static SExprInfo* doCreateColumnNodeFromAggFunc(SSchema* pSchema) {
+static SExprInfo* createColumnNodeFromAggFunc(SSchema* pSchema) {
   tExprNode* pExprNode = calloc(1, sizeof(tExprNode));
 
   pExprNode->nodeType = TEXPR_COL_NODE;
diff --git a/source/libs/parser/test/plannerTest.cpp b/source/libs/parser/test/plannerTest.cpp
index cf8463f245..c86e687664 100644
--- a/source/libs/parser/test/plannerTest.cpp
+++ b/source/libs/parser/test/plannerTest.cpp
@@ -182,15 +182,18 @@ TEST(testCase, displayPlan) {
   generateLogicplan("select count(*), first(a), last(b) from `t.1abc` state_window(a)");
   generateLogicplan("select count(*), first(a), last(b) from `t.1abc` session(ts, 20s)");
 
-  // order by + group by column + limit offset + fill
+  // order by + group by column + limit offset
   generateLogicplan("select top(a, 20) k from `t.1abc` order by k asc limit 3 offset 1");
 
+  // fill
+  generateLogicplan("select min(a) from `t.1abc` where ts>now and ts<now+2h interval(1s) fill(linear)");
+
+  // union + union all
+
+
+
   // join
 
-
-  // union
-
-
   // Aggregate(count(*) [count(*) #5056], sum(a) [sum(a) #5057], avg(b) [avg(b) #5058], min(a+b) [min(a+b) #5060])
   // Projection(cols: [a+b #5059]) filters:(nil)
   //  Projection(cols: [ts #0], [a #1], [b #2]) filters:(nil)
diff --git a/source/libs/planner/src/planner.c b/source/libs/planner/src/planner.c
index 8e53f231ef..79c7691698 100644
--- a/source/libs/planner/src/planner.c
+++ b/source/libs/planner/src/planner.c
@@ -27,7 +27,7 @@
 #define QNODE_JOIN          7
 #define QNODE_DISTINCT      8
 #define QNODE_SORT          9
-#define QNODE_UNIONALL      10
+#define QNODE_UNION         10
 #define QNODE_TIMEWINDOW    11
 #define QNODE_SESSIONWINDOW 12
 #define QNODE_STATEWINDOW   13
@@ -47,6 +47,7 @@ typedef struct SJoinCond {
 static SArray* createQueryPlanImpl(SQueryStmtInfo* pQueryInfo);
 static void doDestroyQueryNode(SQueryPlanNode* pQueryNode);
 
+int32_t printExprInfo(const char* buf, const SQueryPlanNode* pQueryNode, int32_t len);
 int32_t qOptimizeQueryPlan(struct SQueryPlanNode* pQueryNode) {
   return 0;
 }
@@ -225,8 +226,8 @@ static SQueryPlanNode* doCreateQueryPlanForSingleTableImpl(SQueryStmtInfo* pQuer
 
   for(int32_t i = level - 1; i >= 0; --i) {
     SArray* p = pQueryInfo->exprList[i];
+    size_t  num = taosArrayGetSize(p);
 
-    size_t num = taosArrayGetSize(p);
     bool aggregateFunc = false;
     for(int32_t j = 0; j < num; ++j) {
       SExprInfo* pExpr = (SExprInfo*)taosArrayGetP(p, 0);
@@ -265,10 +266,11 @@ static SQueryPlanNode* doCreateQueryPlanForSingleTableImpl(SQueryStmtInfo* pQuer
   if (pQueryInfo->fillType != TSDB_FILL_NONE) {
     SFillEssInfo* pInfo = calloc(1, sizeof(SFillEssInfo));
     pInfo->fillType = pQueryInfo->fillType;
-    pInfo->val = calloc(pNode->numOfExpr, sizeof(int64_t));
+    pInfo->val      = calloc(pNode->numOfExpr, sizeof(int64_t));
     memcpy(pInfo->val, pQueryInfo->fillVal, pNode->numOfExpr);
 
-    pNode = createQueryNode(QNODE_FILL, "Fill", &pNode, 1, NULL, 0, pInfo);
+    SArray* p = pQueryInfo->exprList[0];  // top expression in select clause
+    pNode = createQueryNode(QNODE_FILL, "Fill", &pNode, 1, p, taosArrayGetSize(p), pInfo);
   }
 
   if (pQueryInfo->order != NULL) {
@@ -433,26 +435,11 @@ static int32_t doPrintPlan(char* buf, SQueryPlanNode* pQueryNode, int32_t level,
     }
 
     case QNODE_PROJECT: {
-      len1 = sprintf(buf + len, "cols: ");
+      len1 = sprintf(buf + len, "cols:");
       assert(len1 > 0);
-
       len += len1;
 
-      for (int32_t i = 0; i < pQueryNode->numOfExpr; ++i) {
-        SExprInfo* pExprInfo = taosArrayGetP(pQueryNode->pExpr, i);
-
-        SSqlExpr* p = &pExprInfo->base;
-        len1 = sprintf(buf + len, "[%s #%d]", p->resSchema.name, p->resSchema.colId);
-        assert(len1 > 0);
-
-        len += len1;
-
-        if (i < pQueryNode->numOfExpr - 1) {
-          len1 = sprintf(buf + len, ", ");
-          len += len1;
-        }
-      }
-
+      len = printExprInfo(buf, pQueryNode, len);
       len1 = sprintf(buf + len, ")");
       len += len1;
 
@@ -463,34 +450,15 @@ static int32_t doPrintPlan(char* buf, SQueryPlanNode* pQueryNode, int32_t level,
     }
 
     case QNODE_AGGREGATE: {
-      for (int32_t i = 0; i < pQueryNode->numOfExpr; ++i) {
-        SExprInfo* pExprInfo = taosArrayGetP(pQueryNode->pExpr, i);
-
-        SSqlExpr* pExpr = &pExprInfo->base;
-        len += sprintf(buf + len, "%s [%s #%d]", pExpr->token, pExpr->resSchema.name, pExpr->resSchema.colId);
-        if (i < pQueryNode->numOfExpr - 1) {
-          len1 = sprintf(buf + len, ", ");
-          len += len1;
-        }
-      }
-
+      len = printExprInfo(buf, pQueryNode, len);
       len1 = sprintf(buf + len, ")\n");
       len += len1;
+
       break;
     }
 
     case QNODE_TIMEWINDOW: {
-      for (int32_t i = 0; i < pQueryNode->numOfExpr; ++i) {
-        SExprInfo* pExprInfo = taosArrayGetP(pQueryNode->pExpr, i);
-
-        SSqlExpr* pExpr = &pExprInfo->base;
-        len += sprintf(buf + len, "%s [%s #%d]", pExpr->token, pExpr->resSchema.name, pExpr->resSchema.colId);
-        if (i < pQueryNode->numOfExpr - 1) {
-          len1 = sprintf(buf + len, ", ");
-          len += len1;
-        }
-      }
-
+      len = printExprInfo(buf, pQueryNode, len);
       len1 = sprintf(buf + len, ") ");
       len += len1;
 
@@ -506,16 +474,7 @@ static int32_t doPrintPlan(char* buf, SQueryPlanNode* pQueryNode, int32_t level,
     }
 
     case QNODE_STATEWINDOW: {
-      for (int32_t i = 0; i < pQueryNode->numOfExpr; ++i) {
-        SExprInfo* pExprInfo = taosArrayGetP(pQueryNode->pExpr, i);
-        SSqlExpr*  pExpr = &pExprInfo->base;
-        len += sprintf(buf + len, "%s [%s #%d]", pExpr->token, pExpr->resSchema.name, pExpr->resSchema.colId);
-        if (i < pQueryNode->numOfExpr - 1) {
-          len1 = sprintf(buf + len, ", ");
-          len += len1;
-        }
-      }
-
+      len = printExprInfo(buf, pQueryNode, len);
       len1 = sprintf(buf + len, ") ");
       len += len1;
 
@@ -526,15 +485,7 @@ static int32_t doPrintPlan(char* buf, SQueryPlanNode* pQueryNode, int32_t level,
     }
 
     case QNODE_SESSIONWINDOW: {
-      for (int32_t i = 0; i < pQueryNode->numOfExpr; ++i) {
-        SExprInfo* pExprInfo = taosArrayGetP(pQueryNode->pExpr, i);
-        SSqlExpr*  pExpr = &pExprInfo->base;
-        len += sprintf(buf + len, "%s [%s #%d]", pExpr->token, pExpr->resSchema.name, pExpr->resSchema.colId);
-        if (i < pQueryNode->numOfExpr - 1) {
-          len1 = sprintf(buf + len, ", ");
-          len += len1;
-        }
-      }
+      len = printExprInfo(buf, pQueryNode, len);
 
       len1 = sprintf(buf + len, ") ");
       len += len1;
@@ -546,18 +497,7 @@ static int32_t doPrintPlan(char* buf, SQueryPlanNode* pQueryNode, int32_t level,
     }
 
     case QNODE_GROUPBY: {
-      for (int32_t i = 0; i < pQueryNode->numOfExpr; ++i) {
-        SExprInfo* pExprInfo = taosArrayGetP(pQueryNode->pExpr, i);
-
-        SSqlExpr* pExpr = &pExprInfo->base;
-        len1 = sprintf(buf + len, "%s [%s #%d]", pExpr->token, pExpr->resSchema.name, pExpr->resSchema.colId);
-
-        len += len1;
-        if (i < pQueryNode->numOfExpr - 1) {
-          len1 = sprintf(buf + len, ", ");
-          len += len1;
-        }
-      }
+      len = printExprInfo(buf, pQueryNode, len);
 
       SGroupbyExpr* pGroupbyExpr = pQueryNode->pExtInfo;
       len1 = sprintf(buf + len, ") groupby_col: ");
@@ -611,18 +551,7 @@ static int32_t doPrintPlan(char* buf, SQueryPlanNode* pQueryNode, int32_t level,
       len1 = sprintf(buf + len, "cols: ");
       len += len1;
 
-      for (int32_t i = 0; i < pQueryNode->numOfExpr; ++i) {
-        SExprInfo* pExprInfo = taosArrayGetP(pQueryNode->pExpr, i);
-        SSchema*   resSchema = &pExprInfo->base.resSchema;
-
-        len1 = sprintf(buf + len, "[%s #%d]", resSchema->name, resSchema->colId);
-        len += len1;
-
-        if (i < pQueryNode->numOfExpr - 1) {
-          len1 = sprintf(buf + len, ", ");
-          len += len1;
-        }
-      }
+      len = printExprInfo(buf, pQueryNode, len);
 
       len1 = sprintf(buf + len, ")\n");
       len += len1;
@@ -658,6 +587,26 @@ static int32_t doPrintPlan(char* buf, SQueryPlanNode* pQueryNode, int32_t level,
   return len;
 }
 
+int32_t printExprInfo(const char* buf, const SQueryPlanNode* pQueryNode, int32_t len) {
+  int32_t len1 = 0;
+
+  for (int32_t i = 0; i < pQueryNode->numOfExpr; ++i) {
+    SExprInfo* pExprInfo = taosArrayGetP(pQueryNode->pExpr, i);
+
+    SSqlExpr* pExpr = &pExprInfo->base;
+    len1 = sprintf(buf + len, "%s [%s #%d]", pExpr->token, pExpr->resSchema.name, pExpr->resSchema.colId);
+    assert(len1 > 0);
+
+    len += len1;
+    if (i < pQueryNode->numOfExpr - 1) {
+      len1 = sprintf(buf + len, ", ");
+      len += len1;
+    }
+  }
+
+  return len;
+}
+
 int32_t queryPlanToStringImpl(char* buf, SQueryPlanNode* pQueryNode, int32_t level, int32_t totalLen) {
   int32_t len = doPrintPlan(buf, pQueryNode, level, totalLen);