<fix>[TD-10990] fix stddev empty group by json->key

src/client/src/tscServer.c

@@ -1841,7 +1841,7 @@ int tscProcessRetrieveGlobalMergeRsp(SSqlObj *pSql) {
   uint64_t localQueryId = pSql->self;
   qTableQuery(pQueryInfo->pQInfo, &localQueryId);
   bool convertJson = true;
-  if (tscMultiRoundQuery(pQueryInfo, 0)) convertJson = false;
+  if (pQueryInfo->isStddev == true) convertJson = false;
   convertQueryResult(pRes, pQueryInfo, pSql->self, true, convertJson);
 
   code = pRes->code;

src/client/src/tscSubquery.c

@@ -2450,6 +2450,7 @@ int32_t tscHandleFirstRoundStableQuery(SSqlObj *pSql) {
   STableMetaInfo* pTableMetaInfo = tscGetMetaInfo(pNewQueryInfo, 0);
 
   tscInitQueryInfo(pNewQueryInfo);
+  pNewQueryInfo->isStddev = true;     // for json tag
 
   // add the group cond
   pNewQueryInfo->groupbyExpr = pQueryInfo->groupbyExpr;
@@ -3708,7 +3709,7 @@ TAOS_ROW doSetResultRowData(SSqlObj *pSql) {
     int32_t type  = pInfo->field.type;
     int32_t bytes = pInfo->field.bytes;
 
-    if (tscMultiRoundQuery(pQueryInfo, 0) && pQueryInfo->round == 0 && type == TSDB_DATA_TYPE_JSON){  // for json tag compare in the second round of stddev
+    if (pQueryInfo->isStddev && type == TSDB_DATA_TYPE_JSON){  // for json tag compare in the second round of stddev
       pRes->tsrow[j] = pRes->urow[i];
     }else if (!IS_VAR_DATA_TYPE(type) && type != TSDB_DATA_TYPE_JSON) {
       pRes->tsrow[j] = isNull(pRes->urow[i], type) ? NULL : pRes->urow[i];

src/query/inc/qTableMeta.h

@@ -166,6 +166,7 @@ typedef struct SQueryInfo {
   bool               stateWindow;
   bool               globalMerge;
   bool               multigroupResult;
+  bool               isStddev;
 } SQueryInfo;
 
 /**

tests/pytest/stable/json_tag.py

@@ -105,7 +105,6 @@ class TDTestCase:
         tdSql.checkRows(0)
 
         tdSql.query("select jtag->'sex' from db_json_tag_test.jsons1 where jtag?'sex' or jtag?'num'")
-        tdSql.checkData(0, 0, "\"femail\"")
         tdSql.checkRows(3)
 
         tdSql.query("select *,tbname from db_json_tag_test.jsons1 where jtag->'location'='beijing'")
@@ -290,6 +289,11 @@ class TDTestCase:
         tdSql.checkData(1, 2, 1)
         tdSql.checkData(3, 2, 11)
 
+        tdSql.query("select stddev(dataint) from db_json_tag_test.jsons1 group by jtag->'location'")
+        tdSql.checkData(0, 1, None)
+        tdSql.checkData(1, 0, 0.5)
+        tdSql.checkData(2, 0, 0)
+
         # test json->'key'=null
         tdSql.execute("insert into db_json_tag_test.jsons1_9 values('2020-04-17 15:20:00.000', 5, false, 'json19')")
         tdSql.query("select * from db_json_tag_test.jsons1")