diff --git a/src/client/src/tscSecondaryMerge.c b/src/client/src/tscSecondaryMerge.c
index 95d559b4fa2a849a68ba85c91e72d9f3b8efa3a5..b159ffc5a16a408ccde5c9e3cf9a0eb00c1c1a05 100644
--- a/src/client/src/tscSecondaryMerge.c
+++ b/src/client/src/tscSecondaryMerge.c
@@ -324,7 +324,6 @@ void tscCreateLocalReducer(tExtMemBuffer **pMemBuffer, int32_t numOfBuffer, tOrd
     tfree(pReducer->discardData);
     tfree(pReducer->pResultBuf);
     tfree(pReducer->pFinalRes);
-//    tfree(pReducer->pBufForInterpo);
     tfree(pReducer->prevRowOfInput);
 
     pRes->code = TSDB_CODE_TSC_OUT_OF_MEMORY;
@@ -363,7 +362,8 @@ void tscCreateLocalReducer(tExtMemBuffer **pMemBuffer, int32_t numOfBuffer, tOrd
   if (pQueryInfo->fillType != TSDB_FILL_NONE) {
     SFillColInfo* pFillCol = createFillColInfo(pQueryInfo);
     pReducer->pFillInfo = taosInitFillInfo(pQueryInfo->order.order, revisedSTime, pQueryInfo->groupbyExpr.numOfGroupCols,
-                                           4096, numOfCols, pQueryInfo->slidingTime, pQueryInfo->fillType, pFillCol);
+                                           4096, numOfCols, pQueryInfo->slidingTime, pQueryInfo->slidingTimeUnit,
+                                           tinfo.precision, pQueryInfo->fillType, pFillCol);
   }
 
   int32_t startIndex = pQueryInfo->fieldsInfo.numOfOutput - pQueryInfo->groupbyExpr.numOfGroupCols;
@@ -494,7 +494,7 @@ void tscDestroyLocalReducer(SSqlObj *pSql) {
       tscTrace("%p waiting for delete procedure, status: %d", pSql, status);
     }
 
-    taosDestoryFillInfo(pLocalReducer->pFillInfo);
+    pLocalReducer->pFillInfo = taosDestoryFillInfo(pLocalReducer->pFillInfo);
 
     if (pLocalReducer->pCtx != NULL) {
       for (int32_t i = 0; i < pQueryInfo->fieldsInfo.numOfOutput; ++i) {
@@ -980,8 +980,7 @@ static void doFillResult(SSqlObj *pSql, SLocalReducer *pLocalReducer, bool doneO
         }
 
         /* all output for current group are completed */
-        int32_t totalRemainRows =
-            taosGetNumOfResultWithFill(pFillInfo, rpoints, pFillInfo->slidingTime, actualETime);
+        int32_t totalRemainRows = getFilledNumOfRes(pFillInfo, actualETime, pLocalReducer->resColModel->capacity);
         if (totalRemainRows <= 0) {
           break;
         }
@@ -1267,13 +1266,7 @@ bool doGenerateFinalResults(SSqlObj *pSql, SLocalReducer *pLocalReducer, bool no
   
   SFillInfo* pFillInfo = pLocalReducer->pFillInfo;
   if (pFillInfo != NULL) {
-    STableMetaInfo* pTableMetaInfo = tscGetTableMetaInfoFromCmd(pCmd, pCmd->clauseIndex, 0);
-    STableComInfo tinfo = tscGetTableInfo(pTableMetaInfo->pTableMeta);
-  
-    TSKEY ekey = taosGetRevisedEndKey(pQueryInfo->window.ekey, pFillInfo->order, pFillInfo->slidingTime,
-                                      pQueryInfo->slidingTimeUnit, tinfo.precision);
-  
-    taosFillSetStartInfo(pFillInfo, pResBuf->num, ekey);
+    taosFillSetStartInfo(pFillInfo, pResBuf->num, pQueryInfo->window.ekey);
     taosFillCopyInputDataFromOneFilePage(pFillInfo, pResBuf);
   }
   
@@ -1327,23 +1320,15 @@ static bool doBuildFilledResultForGroup(SSqlObj *pSql) {
   SLocalReducer *pLocalReducer = pRes->pLocalReducer;
   SFillInfo *pFillInfo = pLocalReducer->pFillInfo;
 
-  STableMetaInfo *pTableMetaInfo = tscGetMetaInfo(pQueryInfo, 0);
-  STableComInfo tinfo = tscGetTableInfo(pTableMetaInfo->pTableMeta);
-  
-  int8_t p = tinfo.precision;
-
   if (pFillInfo != NULL && taosNumOfRemainRows(pFillInfo) > 0) {
     assert(pQueryInfo->fillType != TSDB_FILL_NONE);
 
     tFilePage *pFinalDataBuf = pLocalReducer->pResultBuf;
-    int64_t    etime = *(int64_t *)(pFinalDataBuf->data + TSDB_KEYSIZE * (pFillInfo->numOfRows - 1));
+    int64_t etime = *(int64_t *)(pFinalDataBuf->data + TSDB_KEYSIZE * (pFillInfo->numOfRows - 1));
 
-    int32_t remain = taosNumOfRemainRows(pFillInfo);
-    TSKEY ekey = taosGetRevisedEndKey(etime, pQueryInfo->order.order, pQueryInfo->slidingTime, pQueryInfo->slidingTimeUnit, p);
-    
     // the first column must be the timestamp column
-    int32_t rows = taosGetNumOfResultWithFill(pFillInfo, remain, ekey, pLocalReducer->resColModel->capacity);
-    if (rows > 0) {  // do interpo
+    int32_t rows = getFilledNumOfRes(pFillInfo, etime, pLocalReducer->resColModel->capacity);
+    if (rows > 0) {  // do fill gap
       doFillResult(pSql, pLocalReducer, false);
     }
 
@@ -1362,10 +1347,7 @@ static bool doHandleLastRemainData(SSqlObj *pSql) {
 
   bool prevGroupCompleted = (!pLocalReducer->discard) && pLocalReducer->hasUnprocessedRow;
 
-  SQueryInfo *    pQueryInfo = tscGetQueryInfoDetail(pCmd, pCmd->clauseIndex);
-  STableMetaInfo *pTableMetaInfo = tscGetMetaInfo(pQueryInfo, 0);
-  
-  STableComInfo tinfo = tscGetTableInfo(pTableMetaInfo->pTableMeta);
+  SQueryInfo *pQueryInfo = tscGetQueryInfoDetail(pCmd, pCmd->clauseIndex);
 
   if ((isAllSourcesCompleted(pLocalReducer) && !pLocalReducer->hasPrevRow) || pLocalReducer->pLocalDataSrc[0] == NULL ||
       prevGroupCompleted) {
@@ -1373,9 +1355,8 @@ static bool doHandleLastRemainData(SSqlObj *pSql) {
     if (pQueryInfo->fillType != TSDB_FILL_NONE) {
       int64_t etime = (pQueryInfo->window.skey < pQueryInfo->window.ekey) ? pQueryInfo->window.ekey : pQueryInfo->window.skey;
 
-      etime = taosGetRevisedEndKey(etime, pQueryInfo->order.order, pQueryInfo->intervalTime,
-                                   pQueryInfo->slidingTimeUnit, tinfo.precision);
-      int32_t rows = taosGetNumOfResultWithFill(pFillInfo, 0, etime, pLocalReducer->resColModel->capacity);
+      assert(pFillInfo->numOfRows == 0);
+      int32_t rows = getFilledNumOfRes(pFillInfo, etime, pLocalReducer->resColModel->capacity);
       if (rows > 0) {  // do interpo
         doFillResult(pSql, pLocalReducer, true);
       }
diff --git a/src/query/inc/qfill.h b/src/query/inc/qfill.h
index 9ea9c8f7cf3df75c182f33ea5122d0752b097334..da1cd8e5de7014d916be47713cdd2de034dc9521 100644
--- a/src/query/inc/qfill.h
+++ b/src/query/inc/qfill.h
@@ -50,7 +50,8 @@ typedef struct SFillInfo {
   char *  nextValues;           // next row of data
   char**  pData;                // original result data block involved in filling data
   int32_t capacityInRows;       // data buffer size in rows
-  
+  int8_t  slidingUnit;          // sliding time unit
+  int8_t  precision;            // time resoluation
   SFillColInfo* pFillCol;       // column info for fill operations
 } SFillInfo;
 
@@ -61,12 +62,13 @@ typedef struct SPoint {
 
 int64_t taosGetIntervalStartTimestamp(int64_t startTime, int64_t slidingTime, char timeUnit, int16_t precision);
 
-SFillInfo* taosInitFillInfo(int32_t order, TSKEY skey, int32_t numOfTags, int32_t capacity,
-                            int32_t numOfCols, int64_t slidingTime, int32_t fillType, SFillColInfo* pFillCol);
+SFillInfo* taosInitFillInfo(int32_t order, TSKEY skey, int32_t numOfTags, int32_t capacity, int32_t numOfCols,
+                            int64_t slidingTime, int8_t slidingUnit, int8_t precision, int32_t fillType,
+                            SFillColInfo* pFillCol);
 
 void taosResetFillInfo(SFillInfo* pFillInfo, TSKEY startTimestamp);
 
-void taosDestoryFillInfo(SFillInfo *pFillInfo);
+void* taosDestoryFillInfo(SFillInfo *pFillInfo);
 
 void taosFillSetStartInfo(SFillInfo* pFillInfo, int32_t numOfRows, TSKEY endKey);
 
@@ -74,9 +76,7 @@ void taosFillCopyInputDataFromFilePage(SFillInfo* pFillInfo, tFilePage** pInput)
 
 void taosFillCopyInputDataFromOneFilePage(SFillInfo* pFillInfo, tFilePage* pInput);
 
-TSKEY taosGetRevisedEndKey(TSKEY ekey, int32_t order, int64_t timeInterval, int8_t slidingTimeUnit, int8_t precision);
-
-int64_t taosGetNumOfResultWithFill(SFillInfo* pFillInfo, int32_t numOfRows, int64_t ekey, int32_t maxNumOfRows);
+int64_t getFilledNumOfRes(SFillInfo* pFillInfo, int64_t ekey, int32_t maxNumOfRows);
 
 int32_t taosNumOfRemainRows(SFillInfo *pFillInfo);
 
diff --git a/src/query/src/qExecutor.c b/src/query/src/qExecutor.c
index 26502a7408610c2d274af33a575946a1244d8da6..18f6ea0f7c3204ee7ffd3bed74a342d9ef45a8a2 100644
--- a/src/query/src/qExecutor.c
+++ b/src/query/src/qExecutor.c
@@ -1466,7 +1466,7 @@ static void teardownQueryRuntimeEnv(SQueryRuntimeEnv *pRuntimeEnv) {
     tfree(pRuntimeEnv->pCtx);
   }
 
-  taosDestoryFillInfo(pRuntimeEnv->pFillInfo);
+  pRuntimeEnv->pFillInfo = taosDestoryFillInfo(pRuntimeEnv->pFillInfo);
 
   destroyResultBuf(pRuntimeEnv->pResultBuf, pQInfo);
   tsdbCleanupQueryHandle(pRuntimeEnv->pQueryHandle);
@@ -3557,9 +3557,7 @@ bool queryHasRemainResults(SQueryRuntimeEnv* pRuntimeEnv) {
    * first result row in the actual result set will fill nothing.
    */
   if (Q_STATUS_EQUAL(pQuery->status, QUERY_COMPLETED)) {
-    TSKEY ekey = taosGetRevisedEndKey(pQuery->window.ekey, pQuery->order.order, pQuery->slidingTime,
-                                         pQuery->slidingTimeUnit, pQuery->precision);
-    int32_t numOfTotal = taosGetNumOfResultWithFill(pFillInfo, remain, ekey, pQuery->rec.capacity);
+    int32_t numOfTotal = getFilledNumOfRes(pFillInfo, pQuery->window.ekey, pQuery->rec.capacity);
     return numOfTotal > 0;
   }
 
@@ -3601,7 +3599,7 @@ static void doCopyQueryResultToMsg(SQInfo *pQInfo, int32_t numOfRows, char *data
   }
 }
 
-int32_t doFillGapsInResults(SQueryRuntimeEnv* pRuntimeEnv, tFilePage **pDst, int32_t numOfRows, int32_t *numOfInterpo) {
+int32_t doFillGapsInResults(SQueryRuntimeEnv* pRuntimeEnv, tFilePage **pDst, int32_t *numOfInterpo) {
   SQInfo* pQInfo = GET_QINFO_ADDR(pRuntimeEnv);
   SQuery *pQuery = pRuntimeEnv->pQuery;
   SFillInfo* pFillInfo = pRuntimeEnv->pFillInfo;
@@ -4013,7 +4011,8 @@ int32_t doInitQInfo(SQInfo *pQInfo, void *param, void *tsdb, int32_t vgId, bool
   if (pQuery->fillType != TSDB_FILL_NONE && !isPointInterpoQuery(pQuery)) {
     SFillColInfo* pColInfo = taosCreateFillColInfo(pQuery);
     pRuntimeEnv->pFillInfo = taosInitFillInfo(pQuery->order.order, 0, 0, pQuery->rec.capacity, pQuery->numOfOutput,
-                                              pQuery->slidingTime, pQuery->fillType, pColInfo);
+                                              pQuery->slidingTime, pQuery->slidingTimeUnit, pQuery->precision,
+                                              pQuery->fillType, pColInfo);
   }
 
   // todo refactor
@@ -4666,13 +4665,11 @@ static void tableIntervalProcess(SQInfo *pQInfo, STableQueryInfo* pTableInfo) {
       limitResults(pRuntimeEnv);
       break;
     } else {
-      TSKEY ekey = taosGetRevisedEndKey(pQuery->window.ekey, pQuery->order.order, pQuery->slidingTime,
-                                        pQuery->slidingTimeUnit, pQuery->precision);
-      taosFillSetStartInfo(pRuntimeEnv->pFillInfo, pQuery->rec.rows, ekey);
+      taosFillSetStartInfo(pRuntimeEnv->pFillInfo, pQuery->rec.rows, pQuery->window.ekey);
       taosFillCopyInputDataFromFilePage(pRuntimeEnv->pFillInfo, (tFilePage**) pQuery->sdata);
       numOfInterpo = 0;
       
-      pQuery->rec.rows = doFillGapsInResults(pRuntimeEnv, (tFilePage **)pQuery->sdata, pQuery->rec.rows, &numOfInterpo);
+      pQuery->rec.rows = doFillGapsInResults(pRuntimeEnv, (tFilePage **)pQuery->sdata, &numOfInterpo);
       if (pQuery->rec.rows > 0 || Q_STATUS_EQUAL(pQuery->status, QUERY_COMPLETED)) {
         limitResults(pRuntimeEnv);
         break;
@@ -4704,8 +4701,7 @@ static void tableQueryImpl(SQInfo *pQInfo) {
      * So, we do keep in this procedure instead of launching retrieve procedure for next results.
      */
     int32_t numOfInterpo = 0;
-    int32_t remain = taosNumOfRemainRows(pRuntimeEnv->pFillInfo);
-    pQuery->rec.rows = doFillGapsInResults(pRuntimeEnv, (tFilePage **)pQuery->sdata, remain, &numOfInterpo);
+    pQuery->rec.rows = doFillGapsInResults(pRuntimeEnv, (tFilePage **)pQuery->sdata, &numOfInterpo);
   
     if (pQuery->rec.rows > 0) {
       limitResults(pRuntimeEnv);
diff --git a/src/query/src/qfill.c b/src/query/src/qfill.c
index 7b3ea5c1f09bac392d4e72f9c5870fc64f427c12..59bf7b423c8d291e0377301cd8afe7d63bd33ab1 100644
--- a/src/query/src/qfill.c
+++ b/src/query/src/qfill.c
@@ -13,8 +13,8 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include "qfill.h"
 #include "os.h"
+#include "qfill.h"
 #include "qextbuffer.h"
 #include "taosdef.h"
 #include "taosmsg.h"
@@ -58,7 +58,7 @@ int64_t taosGetIntervalStartTimestamp(int64_t startTime, int64_t slidingTime, ch
 }
 
 SFillInfo* taosInitFillInfo(int32_t order, TSKEY skey, int32_t numOfTags, int32_t capacity, int32_t numOfCols,
-    int64_t slidingTime, int32_t fillType, SFillColInfo* pFillCol) {
+    int64_t slidingTime, int8_t slidingUnit, int8_t precision, int32_t fillType, SFillColInfo* pFillCol) {
   if (fillType == TSDB_FILL_NONE) {
     return NULL;
   }
@@ -72,8 +72,10 @@ SFillInfo* taosInitFillInfo(int32_t order, TSKEY skey, int32_t numOfTags, int32_
   pFillInfo->pFillCol  = pFillCol;
   pFillInfo->numOfTags = numOfTags;
   pFillInfo->numOfCols = numOfCols;
+  pFillInfo->precision = precision;
   pFillInfo->slidingTime = slidingTime;
-  
+  pFillInfo->slidingUnit = slidingUnit;
+
   pFillInfo->pData = malloc(POINTER_BYTES * numOfCols);
   
   int32_t rowsize = 0;
@@ -102,9 +104,9 @@ void taosResetFillInfo(SFillInfo* pFillInfo, TSKEY startTimestamp) {
   pFillInfo->numOfTotal   = 0;
 }
 
-void taosDestoryFillInfo(SFillInfo* pFillInfo) {
+void* taosDestoryFillInfo(SFillInfo* pFillInfo) {
   if (pFillInfo == NULL) {
-    return;
+    return NULL;
   }
 
   tfree(pFillInfo->prevValues);
@@ -119,6 +121,15 @@ void taosDestoryFillInfo(SFillInfo* pFillInfo) {
   tfree(pFillInfo->pFillCol);
   
   tfree(pFillInfo);
+  return NULL;
+}
+
+static TSKEY taosGetRevisedEndKey(TSKEY ekey, int32_t order, int64_t timeInterval, int8_t slidingTimeUnit, int8_t precision) {
+  if (order == TSDB_ORDER_ASC) {
+    return ekey;
+  } else {
+    return taosGetIntervalStartTimestamp(ekey, timeInterval, slidingTimeUnit, precision);
+  }
 }
 
 void taosFillSetStartInfo(SFillInfo* pFillInfo, int32_t numOfRows, TSKEY endKey) {
@@ -126,8 +137,10 @@ void taosFillSetStartInfo(SFillInfo* pFillInfo, int32_t numOfRows, TSKEY endKey)
     return;
   }
 
+  pFillInfo->endKey = taosGetRevisedEndKey(endKey, pFillInfo->order, pFillInfo->slidingTime, pFillInfo->slidingUnit,
+      pFillInfo->precision);
+
   pFillInfo->rowIdx    = 0;
-  pFillInfo->endKey    = endKey;
   pFillInfo->numOfRows = numOfRows;
   
   // ensure the space
@@ -165,36 +178,29 @@ void taosFillCopyInputDataFromOneFilePage(SFillInfo* pFillInfo, tFilePage* pInpu
   }
 }
 
-TSKEY taosGetRevisedEndKey(TSKEY ekey, int32_t order, int64_t timeInterval, int8_t slidingTimeUnit, int8_t precision) {
-  if (order == TSDB_ORDER_ASC) {
-    return ekey;
-  } else {
-    return taosGetIntervalStartTimestamp(ekey, timeInterval, slidingTimeUnit, precision);
-  }
-}
+int64_t getFilledNumOfRes(SFillInfo* pFillInfo, TSKEY ekey, int32_t maxNumOfRows) {
+  int64_t* tsList = (int64_t*) pFillInfo->pData[0];
 
-static int32_t taosGetTotalNumOfFilledRes(SFillInfo* pFillInfo, const TSKEY* tsArray, int32_t remain,
-    int64_t nInterval, int64_t ekey) {
-  
-  if (remain > 0) {  // still fill gap within current data block, not generating data after the result set.
-    TSKEY lastKey = tsArray[pFillInfo->numOfRows - 1];
-    int32_t total = (int32_t)(labs(lastKey - pFillInfo->start) / nInterval) + 1;
+  int32_t numOfRows = taosNumOfRemainRows(pFillInfo);
+
+  TSKEY ekey1 = taosGetRevisedEndKey(ekey, pFillInfo->order, pFillInfo->slidingTime, pFillInfo->slidingUnit,
+      pFillInfo->precision);
 
-    assert(total >= remain);
-    return total;
+  int64_t numOfRes = -1;
+  if (numOfRows > 0) {  // still fill gap within current data block, not generating data after the result set.
+    TSKEY lastKey = tsList[pFillInfo->numOfRows - 1];
+
+    numOfRes = (int64_t)(labs(lastKey - pFillInfo->start) / pFillInfo->slidingTime) + 1;
+    assert(numOfRes >= numOfRows);
   } else { // reach the end of data
-    if ((ekey < pFillInfo->start && FILL_IS_ASC_FILL(pFillInfo)) ||
-        (ekey > pFillInfo->start && !FILL_IS_ASC_FILL(pFillInfo))) {
+    if ((ekey1 < pFillInfo->start && FILL_IS_ASC_FILL(pFillInfo)) ||
+        (ekey1 > pFillInfo->start && !FILL_IS_ASC_FILL(pFillInfo))) {
       return 0;
-    } else {
-      return (int32_t)(labs(ekey - pFillInfo->start) / nInterval) + 1;
+    } else {  // the numOfRes rows are all filled with specified policy
+      numOfRes = (labs(ekey1 - pFillInfo->start) / pFillInfo->slidingTime) + 1;
     }
   }
-}
 
-int64_t taosGetNumOfResultWithFill(SFillInfo* pFillInfo, int32_t numOfRows, int64_t ekey, int32_t maxNumOfRows) {
-  int32_t numOfRes = taosGetTotalNumOfFilledRes(pFillInfo, (int64_t*) pFillInfo->pData[0], numOfRows,
-                                                pFillInfo->slidingTime, ekey);
   return (numOfRes > maxNumOfRows) ? maxNumOfRows : numOfRes;
 }
 
@@ -496,8 +502,8 @@ int32_t generateDataBlockImpl(SFillInfo* pFillInfo, tFilePage** data, int32_t nu
 
 int64_t taosGenerateDataBlock(SFillInfo* pFillInfo, tFilePage** output, int32_t capacity) {
   int32_t remain = taosNumOfRemainRows(pFillInfo);  // todo use iterator?
-  int32_t rows   = taosGetNumOfResultWithFill(pFillInfo, remain, pFillInfo->endKey, capacity);
 
+  int32_t rows = getFilledNumOfRes(pFillInfo, pFillInfo->endKey, capacity);
   int32_t numOfRes = generateDataBlockImpl(pFillInfo, output, remain, rows, pFillInfo->pData);
   assert(numOfRes == rows);