From b6edb74b3bdc350b151b375a418d3b22ddd0773a Mon Sep 17 00:00:00 2001
From: shenglian zhou <slzhou@taosdata.com>
Date: Wed, 21 Jul 2021 14:49:36 +0800
Subject: [PATCH] [TD-5431]<fix>:taken into accout data length when compare
 nchar bytes

---
 src/query/src/qExtbuffer.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/query/src/qExtbuffer.c b/src/query/src/qExtbuffer.c
index 90734e2e0e..e14ffa3a28 100644
--- a/src/query/src/qExtbuffer.c
+++ b/src/query/src/qExtbuffer.c
@@ -378,11 +378,18 @@ static FORCE_INLINE int32_t columnValueAscendingComparator(char *f1, char *f2, i
 
     };
     case TSDB_DATA_TYPE_NCHAR: { // todo handle the var string compare
-      int32_t ret = tasoUcs4Compare(f1, f2, bytes);
-      if (ret == 0) {
-        return 0;
+      int32_t len1 = varDataLen(f1);
+      int32_t len2 = varDataLen(f2);
+
+      if (len1 != len2) {
+        return len1 > len2 ? 1 : -1;
+      } else {
+        int32_t ret = tasoUcs4Compare(varDataVal(f1), varDataVal(f2), len1);
+        if (ret == 0) {
+          return 0;
+        }
+        return (ret < 0) ? -1 : 1;
       }
-      return (ret < 0) ? -1 : 1;
     };
     case TSDB_DATA_TYPE_UTINYINT:  DEFAULT_COMP(GET_UINT8_VAL(f1), GET_UINT8_VAL(f2));
     case TSDB_DATA_TYPE_USMALLINT: DEFAULT_COMP(GET_UINT16_VAL(f1), GET_UINT16_VAL(f2));
-- 
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