Merge pull request #6956 from taosdata/hotfix/td-5431-master

[TD-5431]<fix>:taken into accout data length when compare nchar bytes

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);
+      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;
+      }
     };
     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));