fix:add json test case

source/dnode/vnode/src/meta/metaTable.c

@@ -605,8 +605,15 @@ static int metaUpdateTableTagVal(SMeta *pMeta, int64_t version, SVAlterTbReq *pA
   if (iCol == 0) {
     // TODO : need to update tag index
   }
-
   ctbEntry.version = version;
+  if(pTagSchema->nCols == 1 && pTagSchema->pSchema[0].type == TSDB_DATA_TYPE_JSON){
+    ctbEntry.ctbEntry.pTags = taosMemoryMalloc(pAlterTbReq->nTagVal);
+    if(ctbEntry.ctbEntry.pTags == NULL){
+      terrno = TSDB_CODE_OUT_OF_MEMORY;
+      goto _err;
+    }
+    memcpy((void*)ctbEntry.ctbEntry.pTags, pAlterTbReq->pTagVal, pAlterTbReq->nTagVal);
+  }else{
     SKVRowBuilder kvrb = {0};
     const SKVRow  pOldTag = (const SKVRow)ctbEntry.ctbEntry.pTags;
     SKVRow        pNewTag = NULL;
@@ -630,6 +637,7 @@ static int metaUpdateTableTagVal(SMeta *pMeta, int64_t version, SVAlterTbReq *pA
 
     ctbEntry.ctbEntry.pTags = tdGetKVRowFromBuilder(&kvrb);
     tdDestroyKVRowBuilder(&kvrb);
+  }
 
   // save to table.db
   metaSaveToTbDb(pMeta, &ctbEntry);
@@ -639,6 +647,7 @@ static int metaUpdateTableTagVal(SMeta *pMeta, int64_t version, SVAlterTbReq *pA
 
   tDecoderClear(&dc1);
   tDecoderClear(&dc2);
+  if (ctbEntry.ctbEntry.pTags) taosMemoryFree((void*)ctbEntry.ctbEntry.pTags);
   if (ctbEntry.pBuf) taosMemoryFree(ctbEntry.pBuf);
   if (stbEntry.pBuf) tdbFree(stbEntry.pBuf);
   tdbTbcClose(pTbDbc);