diff --git a/source/client/src/clientImpl.c b/source/client/src/clientImpl.c
index f91ceb31840bbf8dccd9144d5a12a41e7f2f358a..5ebc2729f8b4a2d87316c5d317e0b4c8667edf88 100644
--- a/source/client/src/clientImpl.c
+++ b/source/client/src/clientImpl.c
@@ -1672,7 +1672,12 @@ static int32_t doConvertJson(SReqResultInfo* pResultInfo, int32_t numOfCols, int
       break;
     }
   }
-  if (!needConvert) return TSDB_CODE_SUCCESS;
+
+  if (!needConvert) {
+    return TSDB_CODE_SUCCESS;
+  }
+
+  tscDebug("start to convert form json format string");
 
   char*   p = (char*)pResultInfo->pData;
   int32_t dataLen = estimateJsonLen(pResultInfo, numOfCols, numOfRows);
diff --git a/source/common/src/tdatablock.c b/source/common/src/tdatablock.c
index bcb96dafcc6686b4a1aae4c9eada795911fdc6f6..16b8e55cf7a1fe57d9e984ad6d434297794aa07d 100644
--- a/source/common/src/tdatablock.c
+++ b/source/common/src/tdatablock.c
@@ -2120,6 +2120,7 @@ void blockEncode(const SSDataBlock* pBlock, char* data, int32_t* dataLen, int32_
   int32_t* rows = (int32_t*)data;
   *rows = pBlock->info.rows;
   data += sizeof(int32_t);
+  ASSERT(*rows > 0);
 
   int32_t* cols = (int32_t*)data;
   *cols = numOfCols;
@@ -2183,6 +2184,8 @@ void blockEncode(const SSDataBlock* pBlock, char* data, int32_t* dataLen, int32_
 
   *actualLen = *dataLen;
   *groupId = pBlock->info.groupId;
+  ASSERT(*dataLen > 0);
+  uDebug("build data block, actualLen:%d, rows:%d, cols:%d", *dataLen, *rows, *cols);
 }
 
 const char* blockDecode(SSDataBlock* pBlock, const char* pData) {
diff --git a/source/libs/executor/src/dataDeleter.c b/source/libs/executor/src/dataDeleter.c
index 06b7c13fa2cb52b8255098c5efb652d56ec57974..40198615eab8a00a09479693193306026b4ba938 100644
--- a/source/libs/executor/src/dataDeleter.c
+++ b/source/libs/executor/src/dataDeleter.c
@@ -168,7 +168,9 @@ static void getDataLength(SDataSinkHandle* pHandle, int64_t* pLen, bool* pQueryE
   taosReadQitem(pDeleter->pDataBlocks, (void**)&pBuf);
   memcpy(&pDeleter->nextOutput, pBuf, sizeof(SDataDeleterBuf));
   taosFreeQitem(pBuf);
-  *pLen = ((SDataCacheEntry*)(pDeleter->nextOutput.pData))->dataLen;
+
+  SDataCacheEntry* pEntry = (SDataCacheEntry*)pDeleter->nextOutput.pData;
+  *pLen = pEntry->dataLen;
   *pQueryEnd = pDeleter->queryEnd;
   qDebug("got data len %" PRId64 ", row num %d in sink", *pLen, ((SDataCacheEntry*)(pDeleter->nextOutput.pData))->numOfRows);
 }
diff --git a/source/libs/executor/src/dataDispatcher.c b/source/libs/executor/src/dataDispatcher.c
index 20396046ba5daa34c3caaf76796c2b8a3b06527c..1697ed63fb196aa2a571aa26f8ffe29ee1d6c5d5 100644
--- a/source/libs/executor/src/dataDispatcher.c
+++ b/source/libs/executor/src/dataDispatcher.c
@@ -93,6 +93,8 @@ static void toDataCacheEntry(SDataDispatchHandle* pHandle, const SInputData* pIn
 
   pBuf->useSize = sizeof(SDataCacheEntry);
   blockEncode(pInput->pData, pEntry->data, &pEntry->dataLen, numOfCols, pEntry->compressed);
+  ASSERT(pEntry->numOfRows == *(int32_t*)(pEntry->data+8));
+  ASSERT(pEntry->numOfCols == *(int32_t*)(pEntry->data+8+4));
 
   pBuf->useSize += pEntry->dataLen;
 
@@ -170,7 +172,13 @@ static void getDataLength(SDataSinkHandle* pHandle, int64_t* pLen, bool* pQueryE
   taosReadQitem(pDispatcher->pDataBlocks, (void**)&pBuf);
   memcpy(&pDispatcher->nextOutput, pBuf, sizeof(SDataDispatchBuf));
   taosFreeQitem(pBuf);
-  *pLen = ((SDataCacheEntry*)(pDispatcher->nextOutput.pData))->dataLen;
+
+  SDataCacheEntry* pEntry = (SDataCacheEntry*)pDispatcher->nextOutput.pData;
+  *pLen = pEntry->dataLen;
+
+  ASSERT(pEntry->numOfRows == *(int32_t*)(pEntry->data+8));
+  ASSERT(pEntry->numOfCols == *(int32_t*)(pEntry->data+8+4));
+
   *pQueryEnd = pDispatcher->queryEnd;
   qDebug("got data len %" PRId64 ", row num %d in sink", *pLen, ((SDataCacheEntry*)(pDispatcher->nextOutput.pData))->numOfRows);
 }
@@ -191,6 +199,9 @@ static int32_t getDataBlock(SDataSinkHandle* pHandle, SOutputData* pOutput) {
   pOutput->numOfCols = pEntry->numOfCols;
   pOutput->compressed = pEntry->compressed;
 
+  ASSERT(pEntry->numOfRows == *(int32_t*)(pEntry->data+8));
+  ASSERT(pEntry->numOfCols == *(int32_t*)(pEntry->data+8+4));
+
   atomic_sub_fetch_64(&pDispatcher->cachedSize, pEntry->dataLen);
   atomic_sub_fetch_64(&gDataSinkStat.cachedSize, pEntry->dataLen);