diff --git a/deps/oblib/src/lib/charset/ob_ctype_os.cc b/deps/oblib/src/lib/charset/ob_ctype_os.cc
index db547bef374d63077a5f753bdd319b515dfc4f94..dfaf7ee8cd5d9bc5766a8d24a23040eb3eee4fd6 100644
--- a/deps/oblib/src/lib/charset/ob_ctype_os.cc
+++ b/deps/oblib/src/lib/charset/ob_ctype_os.cc
@@ -48,7 +48,7 @@ ob_convert_internal(char *to, uint32 to_length,
       error_num++;
     } else {
       // Not enough characters
-      if (!trim_incomplete_tail && cnvres != OB_CS_TOOSMALL) {
+      if (!trim_incomplete_tail && (const uchar*) from < from_end) {
         error_num++;
         from++;
         wc= replaced_char;
diff --git a/src/sql/engine/expr/ob_expr_nlssort.cpp b/src/sql/engine/expr/ob_expr_nlssort.cpp
index 25165ac39d272258c4be0a441ad9bddfe0ed3efd..838a95b2d7be8b4a2605961235f0bb84cafdb398 100644
--- a/src/sql/engine/expr/ob_expr_nlssort.cpp
+++ b/src/sql/engine/expr/ob_expr_nlssort.cpp
@@ -105,7 +105,7 @@ int ObExprNLSSort::convert_to_coll_code(ObEvalCtx &ctx,
     } else {
       to_str.assign_ptr(conv_buf, result_len);
     }
-    LOG_DEBUG("charset convert", K(from_str), K(from_type), K(to_str), K(result_len));
+    LOG_DEBUG("charset convert", KPHEX(from_str.ptr(), from_str.length()), K(from_type), K(to_type), KPHEX(to_str.ptr(), to_str.length()), K(result_len));
   } else { 
     to_str.assign_ptr(from_str.ptr(), from_str.length());
   }