diff --git a/src/client/src/tscUtil.c b/src/client/src/tscUtil.c
index d494700715fe411efff4b95288538dbe1f72a4ec..810ad6347c05cebb325144a3866a8a8f42d99985 100644
--- a/src/client/src/tscUtil.c
+++ b/src/client/src/tscUtil.c
@@ -189,7 +189,7 @@ bool tscIsProjectionQueryOnSTable(SQueryInfo* pQueryInfo, int32_t tableIndex) {
   
   /*
    * In following cases, return false for non ordered project query on super table
-   * 1. failed to get metermeta from server; 2. not a super table; 3. limitation is 0;
+   * 1. failed to get tableMeta from server; 2. not a super table; 3. limitation is 0;
    * 4. show queries, instead of a select query
    */
   size_t numOfExprs = tscSqlExprNumOfExprs(pQueryInfo);
@@ -198,11 +198,6 @@ bool tscIsProjectionQueryOnSTable(SQueryInfo* pQueryInfo, int32_t tableIndex) {
     return false;
   }
   
-  // only query on tag, a project query
-  if (tscQueryTags(pQueryInfo)) {
-    return true;
-  }
-  
   for (int32_t i = 0; i < numOfExprs; ++i) {
     int32_t functionId = tscSqlExprGet(pQueryInfo, i)->functionId;
     if (functionId != TSDB_FUNC_PRJ && functionId != TSDB_FUNC_TAGPRJ && functionId != TSDB_FUNC_TAG &&
@@ -221,7 +216,7 @@ bool tscNonOrderedProjectionQueryOnSTable(SQueryInfo* pQueryInfo, int32_t tableI
   }
   
   // order by columnIndex exists, not a non-ordered projection query
-  return pQueryInfo->order.orderColId < 0 && pQueryInfo->order.orderColId != TSDB_TBNAME_COLUMN_INDEX;
+  return pQueryInfo->order.orderColId < 0;
 }
 
 bool tscOrderedProjectionQueryOnSTable(SQueryInfo* pQueryInfo, int32_t tableIndex) {
diff --git a/src/query/src/qExecutor.c b/src/query/src/qExecutor.c
index ce5286af5873abab81edc8bdf0ee52ed699a3a36..534ed4bfd478a5d253c906c2ebb3ce6fcfd3ba98 100644
--- a/src/query/src/qExecutor.c
+++ b/src/query/src/qExecutor.c
@@ -789,11 +789,10 @@ static char *getDataBlock(SQueryRuntimeEnv *pRuntimeEnv, SArithmeticSupport *sas
     sas->data    = calloc(pQuery->numOfCols, POINTER_BYTES);
 
     // here the pQuery->colList and sas->colList are identical
+    int32_t numOfCols = taosArrayGetSize(pDataBlock);
     for (int32_t i = 0; i < pQuery->numOfCols; ++i) {
       SColumnInfo *pColMsg = &pQuery->colList[i];
 
-      int32_t numOfCols = taosArrayGetSize(pDataBlock);
-
       dataBlock = NULL;
       for (int32_t k = 0; k < numOfCols; ++k) {  //todo refactor
         SColumnInfoData *p = taosArrayGet(pDataBlock, k);
@@ -2102,7 +2101,8 @@ static void ensureOutputBuffer(SQueryRuntimeEnv* pRuntimeEnv, SDataBlockInfo* pB
       
       for (int32_t i = 0; i < pQuery->numOfOutput; ++i) {
         int32_t bytes = pQuery->pSelectExpr[i].bytes;
-        
+        assert(bytes > 0 && newSize > 0);
+
         char *tmp = realloc(pQuery->sdata[i], bytes * newSize + sizeof(tFilePage));
         if (tmp == NULL) {  // todo handle the oom
           assert(0);
@@ -5501,7 +5501,7 @@ static SQInfo *createQInfoImpl(SQueryTableMsg *pQueryMsg, SArray* pTableIdList,
   }
 
   // set the output buffer capacity
-  pQuery->rec.capacity = 2;
+  pQuery->rec.capacity = 4096;
   pQuery->rec.threshold = 4000;
 
   for (int32_t col = 0; col < pQuery->numOfOutput; ++col) {
diff --git a/src/query/src/qsyntaxtreefunction.c b/src/query/src/qsyntaxtreefunction.c
index 41e84b5ab02bab0599ae95388780364edf32d672..5719bb0188d6739d327112631c4a0fc82335fb30 100644
--- a/src/query/src/qsyntaxtreefunction.c
+++ b/src/query/src/qsyntaxtreefunction.c
@@ -311,7 +311,7 @@ void calc_fn_i32_i32_sub(void *left, void *right, int32_t numLeft, int32_t numRi
   if (numLeft == numRight) {
     for (; i >= 0 && i < numRight; i += step, pOutput += 1) {
       if (isNull((char *)&(pLeft[i]), TSDB_DATA_TYPE_INT) || isNull((char *)&(pRight[i]), TSDB_DATA_TYPE_INT)) {
-        setNull((char *)&(pOutput[i]), TSDB_DATA_TYPE_DOUBLE, tDataTypeDesc[TSDB_DATA_TYPE_DOUBLE].nSize);
+        setNull((char *)(pOutput), TSDB_DATA_TYPE_DOUBLE, tDataTypeDesc[TSDB_DATA_TYPE_DOUBLE].nSize);
         continue;
       }
       *pOutput = (double)pLeft[i] - pRight[i];