From 16219bc630431f55e5565b9d6147592d244a4573 Mon Sep 17 00:00:00 2001
From: Haojun Liao <hjliao@taosdata.com>
Date: Thu, 5 Nov 2020 19:15:20 +0800
Subject: [PATCH] [TD-225]

---
 src/client/src/tscSubquery.c | 4 ++++
 src/util/src/tcompare.c      | 9 ++++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/client/src/tscSubquery.c b/src/client/src/tscSubquery.c
index 9905de279e..fd56001174 100644
--- a/src/client/src/tscSubquery.c
+++ b/src/client/src/tscSubquery.c
@@ -853,11 +853,15 @@ static void tidTagRetrieveCallback(void* param, TAOS_RES* tres, int32_t numOfRow
   }
 
   if (taosArrayGetSize(s1) == 0 || taosArrayGetSize(s2) == 0) {  // no results,return.
+    assert(pParentSql->fp != tscJoinQueryCallback);
+
     tscDebug("%p tag intersect does not generated qualified tables for join, free all sub SqlObj and quit", pParentSql);
     freeJoinSubqueryObj(pParentSql);
 
     // set no result command
     pParentSql->cmd.command = TSDB_SQL_RETRIEVE_EMPTY_RESULT;
+    assert(pParentSql->fp != tscJoinQueryCallback);
+
     (*pParentSql->fp)(pParentSql->param, pParentSql, 0);
   } else {
     // proceed to for ts_comp query
diff --git a/src/util/src/tcompare.c b/src/util/src/tcompare.c
index ba711ced8f..1090ab8101 100644
--- a/src/util/src/tcompare.c
+++ b/src/util/src/tcompare.c
@@ -367,7 +367,14 @@ int32_t doCompare(const char* f1, const char* f2, int32_t type, size_t size) {
     case TSDB_DATA_TYPE_TINYINT:
     case TSDB_DATA_TYPE_BOOL:       DEFAULT_COMP(GET_INT8_VAL(f1), GET_INT8_VAL(f2));
     case TSDB_DATA_TYPE_NCHAR: {
-      int32_t ret = wcsncmp((wchar_t*) f1, (wchar_t*) f2, size/TSDB_NCHAR_SIZE);
+      tstr* t1 = (tstr*) f1;
+      tstr* t2 = (tstr*) f2;
+
+      if (t1->len != t2->len) {
+        return t1->len > t2->len? 1:-1;
+      }
+
+      int32_t ret = wcsncmp((wchar_t*) t1->data, (wchar_t*) t2->data, t2->len/TSDB_NCHAR_SIZE);
       if (ret == 0) {
         return ret;
       }