diff --git a/source/client/src/clientSml.c b/source/client/src/clientSml.c
index 8b2f47b2958270b37631966808619f0a80089edc..68c47c2d13421cd34e327db37e31ae76774985ac 100644
--- a/source/client/src/clientSml.c
+++ b/source/client/src/clientSml.c
@@ -726,9 +726,6 @@ static int64_t smlGetTimeValue(const char *value, int32_t len, int8_t type) {
   if(value + len != endPtr){
     return -1;
   }
-  if(tsInt64 == 0){
-    return taosGetTimestampNs();
-  }
   double ts = tsInt64;
   switch (type) {
     case TSDB_TIME_PRECISION_HOURS:
@@ -794,8 +791,8 @@ static int8_t smlGetTsTypeByPrecision(int8_t precision) {
 }
 
 static int64_t smlParseInfluxTime(SSmlHandle* info, const char* data, int32_t len){
-  if(len == 0){
-    return taosGetTimestamp(TSDB_TIME_PRECISION_NANO);
+  if(len == 0 || (len == 1 && data[0] == '0')){
+    return taosGetTimestampNs();
   }
 
   int8_t tsType = smlGetTsTypeByPrecision(info->precision);
@@ -817,6 +814,9 @@ static int64_t smlParseOpenTsdbTime(SSmlHandle* info, const char* data, int32_t
     smlBuildInvalidDataMsg(&info->msgBuf, "timestamp can not be null", NULL);
     return -1;
   }
+  if(len == 1 && data[0] == '0'){
+    return taosGetTimestampNs();
+  }
   int8_t tsType = smlGetTsTypeByLen(len);
   if (tsType == -1) {
     smlBuildInvalidDataMsg(&info->msgBuf, "timestamp precision can only be seconds(10 digits) or milli seconds(13 digits)", data);
diff --git a/source/common/src/tglobal.c b/source/common/src/tglobal.c
index b8dd33b9159bcfb92dc4ed713335cbe96fce7d70..1b61a0bc606aa9fd479cf996668756d2b88f4702 100644
--- a/source/common/src/tglobal.c
+++ b/source/common/src/tglobal.c
@@ -78,7 +78,7 @@ char     tsTelemServer[TSDB_FQDN_LEN] = "telemetry.taosdata.com";
 uint16_t tsTelemPort = 80;
 
 // schemaless
-char tsSmlTagName[TSDB_COL_NAME_LEN] = "__tag";
+char tsSmlTagName[TSDB_COL_NAME_LEN] = "_tag_null";
 char tsSmlChildTableName[TSDB_TABLE_NAME_LEN] = ""; //user defined child table name can be specified in tag value.
                                                      //If set to empty system will generate table name using MD5 hash.
 bool tsSmlDataFormat = true;  // true means that the name and order of cols in each line are the same(only for influx protocol)
@@ -327,7 +327,7 @@ static int32_t taosAddClientCfg(SConfig *pCfg) {
   if (cfgAddBool(pCfg, "keepColumnName", tsKeepOriginalColumnName, 1) != 0) return -1;
   if (cfgAddInt32(pCfg, "queryPolicy", tsQueryPolicy, 1, 3, 1) != 0) return -1;
   if (cfgAddString(pCfg, "smlChildTableName", "", 1) != 0) return -1;
-  if (cfgAddString(pCfg, "smlTagName", "", 1) != 0) return -1;
+  if (cfgAddString(pCfg, "smlTagNullName", tsSmlTagName, 1) != 0) return -1;
   if (cfgAddBool(pCfg, "smlDataFormat", tsSmlDataFormat, 1) != 0) return -1;
 
   tsNumOfTaskQueueThreads = tsNumOfCores / 4;
@@ -524,7 +524,7 @@ static int32_t taosSetClientCfg(SConfig *pCfg) {
   }
 
   tstrncpy(tsSmlChildTableName, cfgGetItem(pCfg, "smlChildTableName")->str, TSDB_TABLE_NAME_LEN);
-  tstrncpy(tsSmlTagName, cfgGetItem(pCfg, "smlTagName")->str, TSDB_COL_NAME_LEN);
+  tstrncpy(tsSmlTagName, cfgGetItem(pCfg, "smlTagNullName")->str, TSDB_COL_NAME_LEN);
   tsSmlDataFormat = cfgGetItem(pCfg, "smlDataFormat")->bval;
 
   tsShellActivityTimer = cfgGetItem(pCfg, "shellActivityTimer")->i32;