1. Some optimization when conversion is not needed.

2. One now must pass length argument into append(const char *str, uint length),
length is not calculated internally anymore.

sql/sql_select.cc

@@ -9261,7 +9261,9 @@ static void select_describe(JOIN *join, bool need_tmp_table, bool need_order,
           {
             if (tmp1.length())
               tmp1.append(',');
-            tmp1.append(table->key_info[j].name, 0, system_charset_info);
+            tmp1.append(table->key_info[j].name, 
+			strlen(table->key_info[j].name),
+			system_charset_info);
           }
         }
       }
@@ -9281,7 +9283,8 @@ static void select_describe(JOIN *join, bool need_tmp_table, bool need_order,
 	{
 	  if (tmp2.length())
 	    tmp2.append(',');
-	  tmp2.append((*ref)->name(), 0, system_charset_info);
+	  tmp2.append((*ref)->name(), strlen((*ref)->name()),
+		      system_charset_info);
 	}
 	item_list.push_back(new Item_string(tmp2.ptr(),tmp2.length(),cs));
       }

sql/sql_show.cc

@@ -1207,7 +1207,7 @@ store_create_info(THD *thd, TABLE *table, String *packet)
 {
   List<Item> field_list;
   char tmp[MAX_FIELD_WIDTH], *for_str, buff[128], *end, *alias;
-  String type(tmp, sizeof(tmp),&my_charset_bin);
+  String type(tmp, sizeof(tmp), system_charset_info);
   Field **ptr,*field;
   uint primary_key;
   KEY *key_info;
@@ -1254,7 +1254,7 @@ store_create_info(THD *thd, TABLE *table, String *packet)
       type.set(tmp, sizeof(tmp),&my_charset_bin);
 
     field->sql_type(type);
-    packet->append(type.ptr(),type.length());
+    packet->append(type.ptr(), type.length(), system_charset_info);
 
     if (field->has_charset() && !limited_mysql_mode && !foreign_db_mode)
     {
@@ -1313,7 +1313,7 @@ store_create_info(THD *thd, TABLE *table, String *packet)
       else if (field->maybe_null())
         packet->append("NULL", 4);                    // Null as default
       else
-        packet->append(tmp,0);
+        packet->append(tmp);
     }
 
     if (!foreign_db_mode && !limited_mysql_mode &&

sql/sql_string.cc

@@ -416,16 +416,18 @@ bool String::append(const String &s)
 
 
 /*
-  Append a latin1 string to the a string of the current character set
+  Append an ASCII string to the a string of the current character set
 */
 
-
 bool String::append(const char *s,uint32 arg_length)
 {
-  if (!arg_length)				// Default argument
-    if (!(arg_length= (uint32) strlen(s)))
-      return FALSE;
-  if (str_charset->mbmaxlen > 1)
+  if (!arg_length)
+    return FALSE;
+
+  /*
+    For an ASCII incompatible string, e.g. UCS-2, we need to convert
+  */
+  if (str_charset->mbminlen > 1)
   {
     uint32 add_length=arg_length * str_charset->mbmaxlen;
     if (realloc(str_length+ add_length))
@@ -434,6 +436,10 @@ bool String::append(const char *s,uint32 arg_length)
 				  s, arg_length, &my_charset_latin1);
     return FALSE;
   }
+
+  /*
+    For an ASCII compatinble string we can just append.
+  */
   if (realloc(str_length+arg_length))
     return TRUE;
   memcpy(Ptr+str_length,s,arg_length);
@@ -442,30 +448,37 @@ bool String::append(const char *s,uint32 arg_length)
 }
 
 
+/*
+  Append a 0-terminated ASCII string
+*/
+
+bool String::append(const char *s)
+{
+  return append(s, strlen(s));
+}
+
+
 /*
   Append a string in the given charset to the string
   with character set recoding
 */
 
-
 bool String::append(const char *s,uint32 arg_length, CHARSET_INFO *cs)
 {
   uint32 dummy_offset;
-  uint32 add_length;
-
-  if (!arg_length && !(arg_length= (uint32)strlen(s)))
-      return FALSE;
-
-  add_length= arg_length * str_charset->mbmaxlen;
-  if (realloc(str_length + add_length)) 
-    return TRUE;
+  
   if (needs_conversion(arg_length, cs, str_charset, &dummy_offset))
   {
+    uint32 add_length= arg_length / cs->mbminlen * str_charset->mbmaxlen;
+    if (realloc(str_length + add_length)) 
+      return TRUE;
     str_length+= copy_and_convert(Ptr+str_length, add_length, str_charset,
 				  s, arg_length, cs);
   }
   else
   {
+    if (realloc(str_length + arg_length)) 
+      return TRUE;
     memcpy(Ptr + str_length, s, arg_length);
     str_length+= arg_length;
   }

sql/sql_string.h

@@ -190,7 +190,8 @@ class String
   bool copy(const char*s,uint32 arg_length, CHARSET_INFO *csfrom,
 	    CHARSET_INFO *csto);
   bool append(const String &s);
-  bool append(const char *s,uint32 arg_length=0);
+  bool append(const char *s);
+  bool append(const char *s,uint32 arg_length);
   bool append(const char *s,uint32 arg_length, CHARSET_INFO *cs);
   bool append(IO_CACHE* file, uint32 arg_length);
   bool append_with_prefill(const char *s, uint32 arg_length,