diff --git a/src/system/detail/src/vnodeQueryImpl.c b/src/system/detail/src/vnodeQueryImpl.c
index c1224a11391f11cbfd8b0db3f087e628d86bb516..dd618c0321e030bc18007aa5ffeb498a9c9288ce 100644
--- a/src/system/detail/src/vnodeQueryImpl.c
+++ b/src/system/detail/src/vnodeQueryImpl.c
@@ -4525,10 +4525,11 @@ static void doSetTagValueInParam(tTagSchema *pTagSchema, int32_t tagColIdx, SMet
   SSchema *pCol = &pTagSchema->pSchema[tagColIdx];
 
   tVariantDestroy(param);
-  tVariantCreateFromBinary(param, pStr, pCol->bytes, pCol->type);
 
   if (isNull(pStr, pCol->type)) {
     param->nType = TSDB_DATA_TYPE_NULL;
+  } else {
+    tVariantCreateFromBinary(param, pStr, pCol->bytes, pCol->type);
   }
 }
 
@@ -5993,10 +5994,13 @@ int32_t getDataBlocksForMeters(SMeterQuerySupportObj *pSupporter, SQuery *pQuery
     size_t  bufferSize = size + sizeof(TSCKSUM);
     
     pMeterDataInfo[j]->numOfBlocks = compInfo.numOfBlocks;
-    pMeterDataInfo[j]->pBlock = calloc(1, bufferSize);
-    if (pMeterDataInfo[j]->pBlock == NULL) {
+    char* p = realloc(pMeterDataInfo[j]->pBlock, bufferSize);
+    if (p == NULL) {
       clearAllMeterDataBlockInfo(pMeterDataInfo, 0, numOfMeters);
       return TSDB_CODE_SERV_OUT_OF_MEMORY;
+    } else {
+      memset(p, 0, bufferSize);
+      pMeterDataInfo[j]->pBlock = (SCompBlock*) p;
     }
   
     read(pVnodeFileInfo->headerFd, pMeterDataInfo[j]->pBlock, bufferSize);
diff --git a/src/system/detail/src/vnodeQueryProcess.c b/src/system/detail/src/vnodeQueryProcess.c
index c87229971f956f39e6d0dc0936cfa5643d1d4ba8..f4197ab22417b6ed7c1d8e11eb9f8dad5f7296d2 100644
--- a/src/system/detail/src/vnodeQueryProcess.c
+++ b/src/system/detail/src/vnodeQueryProcess.c
@@ -573,10 +573,10 @@ static void vnodeMultiMeterMultiOutputProcessor(SQInfo *pQInfo) {
   tSidSet *pSids = pSupporter->pSidSet;
 
   SMeterObj *pOneMeter = getMeterObj(pSupporter->pMeterObj, pMeterSidExtInfo[0]->sid);
-
-  resetCtxOutputBuf(pRuntimeEnv);
-
+  
   if (isPointInterpoQuery(pQuery)) {
+    resetCtxOutputBuf(pRuntimeEnv);
+  
     assert(pQuery->limit.offset == 0 && pQuery->limit.limit != 0);
 
     while (pSupporter->subgroupIdx < pSids->numOfSubSet) {
@@ -663,7 +663,9 @@ static void vnodeMultiMeterMultiOutputProcessor(SQInfo *pQInfo) {
     if (pSupporter->meterIdx >= pSids->numOfSids) {
       return;
     }
-
+  
+    resetCtxOutputBuf(pRuntimeEnv);
+  
     for (int32_t i = 0; i < pRuntimeEnv->usedIndex; ++i) {
       SOutputRes *pOneRes = &pRuntimeEnv->pResult[i];
       clearGroupResultBuf(pOneRes, pQuery->numOfOutputCols);