[TD-4199]<feature> enhance performance

src/client/src/tscSQLParser.c

@@ -8306,6 +8306,7 @@ static int32_t doLoadAllTableMeta(SSqlObj* pSql, SQueryInfo* pQueryInfo, SSqlNod
     STableMetaVgroupInfo* p = taosHashGet(pCmd->pTableMetaMap, fname, strnlen(fname, TSDB_TABLE_FNAME_LEN));
 
     pTableMetaInfo->pTableMeta        = tscTableMetaDup(p->pTableMeta);
+    pTableMetaInfo->tableMetaCapacity = tscGetTableMetaSize(pTableMetaInfo->pTableMeta);
     assert(pTableMetaInfo->pTableMeta != NULL);
 
     if (p->vgroupIdList != NULL) {
@@ -8406,6 +8407,7 @@ static int32_t doValidateSubquery(SSqlNode* pSqlNode, int32_t index, SSqlObj* pS
     return TSDB_CODE_TSC_OUT_OF_MEMORY;
   }
   pTableMetaInfo1->pTableMeta        = extractTempTableMetaFromSubquery(pSub);
+  pTableMetaInfo1->tableMetaCapacity = tscGetTableMetaSize(pTableMetaInfo1->pTableMeta);
 
   if (subInfo->aliasName.n > 0) {
     if (subInfo->aliasName.n >= TSDB_TABLE_FNAME_LEN) {

src/client/src/tscServer.c

@@ -2845,8 +2845,10 @@ int32_t tscGetTableMetaImpl(SSqlObj* pSql, STableMetaInfo *pTableMetaInfo, bool
 
   size_t len = strlen(name);
   if (pTableMetaInfo->tableMetaCapacity != 0) {
+    if (pTableMetaInfo->pTableMeta != NULL) {
       memset(pTableMetaInfo->pTableMeta, 0, pTableMetaInfo->tableMetaCapacity);
     } 
+  } 
   taosHashGetCloneExt(tscTableMetaMap, name, len, NULL, (void **)&(pTableMetaInfo->pTableMeta), &pTableMetaInfo->tableMetaCapacity);
 
   STableMeta* pMeta = pTableMetaInfo->pTableMeta;