bugfix: create internal temporary tables in mysql_tmpdir, not in datadir

sql/sql_select.cc

@@ -10092,7 +10092,7 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
   bool  using_unique_constraint= 0;
   bool  use_packed_rows= 0;
   bool  not_all_columns= !(select_options & TMP_TABLE_ALL_COLUMNS);
-  char  *tmpname,path[FN_REFLEN], tmp_table_name[50];
+  char  *tmpname,path[FN_REFLEN];
   uchar	*pos, *group_buff, *bitmaps;
   uchar *null_flags;
   Field **reg_field, **from_field, **default_field;
@@ -10123,12 +10123,12 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
     temp_pool_slot = bitmap_lock_set_next(&temp_pool);
 
   if (temp_pool_slot != MY_BIT_NONE) // we got a slot
-    sprintf(tmp_table_name, "%s_%lx_%i", tmp_file_prefix,
+    sprintf(path, "%s_%lx_%i", tmp_file_prefix,
             current_pid, temp_pool_slot);
   else
   {
     /* if we run out of slots or we are not using tempool */
-    sprintf(tmp_table_name, "%s%lx_%lx_%x", tmp_file_prefix,current_pid,
+    sprintf(path, "%s%lx_%lx_%x", tmp_file_prefix,current_pid,
             thd->thread_id, thd->tmp_table++);
   }
 
@@ -10136,7 +10136,7 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
     No need to change table name to lower case as we are only creating
     MyISAM, Maria or HEAP tables here
   */
-  fn_format(path, tmp_table_name, mysql_tmpdir, "",
+  fn_format(path, path, mysql_tmpdir, "",
             MY_REPLACE_EXT|MY_UNPACK_FILENAME);
 
   if (group)
@@ -10183,7 +10183,7 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
                         sizeof(*key_part_info)*(param->group_parts+1),
                         &param->start_recinfo,
                         sizeof(*param->recinfo)*(field_count*2+4),
-                        &tmpname, (uint) strlen(tmp_table_name)+1,
+                        &tmpname, (uint) strlen(path)+1,
                         &group_buff, (group && ! using_unique_constraint ?
                                       param->group_length : 0),
                         &bitmaps, bitmap_buffer_size(field_count)*2,
@@ -10202,7 +10202,7 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
     DBUG_RETURN(NULL);				/* purecov: inspected */
   }
   param->items_to_copy= copy_func;
-  strmov(tmpname, tmp_table_name);
+  strmov(tmpname, path);
   /* make table according to fields */
 
   bzero((char*) table,sizeof(*table));