[td-1412]

src/query/src/qExecutor.c

@@ -793,7 +793,7 @@ static void doBlockwiseApplyFunctions(SQueryRuntimeEnv *pRuntimeEnv, bool closed
       pCtx[k].startOffset = (QUERY_IS_ASC_QUERY(pQuery)) ? offset : offset - (forwardStep - 1);
 
       if ((aAggs[functionId].nStatus & TSDB_FUNCSTATE_SELECTIVITY) != 0) {
-        pCtx[k].ptsList = &tsBuf[offset];
+        pCtx[k].ptsList = &tsBuf[pCtx[k].startOffset];
       }
 
       // not a whole block involved in query processing, statistics data can not be used
@@ -1475,12 +1475,14 @@ void setExecParams(SQuery *pQuery, SQLFunctionCtx *pCtx, void* inputData, TSKEY
   pCtx->preAggVals.dataBlockLoaded = (inputData != NULL);
 
   // limit/offset query will affect this value
-  pCtx->startOffset = QUERY_IS_ASC_QUERY(pQuery) ? pQuery->pos:0;
   pCtx->size = QUERY_IS_ASC_QUERY(pQuery) ? pBlockInfo->rows - pQuery->pos : pQuery->pos + 1;
 
+  // minimum value no matter ascending/descending order query
+  pCtx->startOffset = QUERY_IS_ASC_QUERY(pQuery) ? pQuery->pos: (pQuery->pos - pCtx->size - 1);
+
   uint32_t status = aAggs[functionId].nStatus;
   if (((status & (TSDB_FUNCSTATE_SELECTIVITY | TSDB_FUNCSTATE_NEED_TS)) != 0) && (tsCol != NULL)) {
-    pCtx->ptsList = tsCol;
+    pCtx->ptsList = &tsCol[pCtx->startOffset];
   }
 
   if (functionId >= TSDB_FUNC_FIRST_DST && functionId <= TSDB_FUNC_LAST_DST) {