Simpler arena swapping code

Now thd->mem_root is a pointer to thd->main_mem_root and THR_MALLOC is a pointer to thd->mem_root.
This gives us the following benefits:
- Allow us to easily detect if arena has already been swapped before (this fixes a bug in setup_conds() where arena was swaped twice in some cases)
- Faster swaps of arenas (as we don't have to copy the whole MEM_ROOT)
- We don't anymore have to call my_pthread_setspecific_ptr(THR_MALLOC,...) to change where memory is alloced. Now it's enough to set thd->mem_root

1 files changed, 1 insertions, 1 deletions

diff --git a/sql/sql_select.h b/sql/sql_select.h
index 34eaa7e272d..bbd169d1850 100644
--- a/sql/sql_select.h
+++ b/sql/sql_select.h
@@ -354,7 +354,7 @@ class store_key :public Sql_alloc
 				   field_arg->table, field_arg->charset());
     else
     {
-      to_field=field_arg->new_field(&thd->mem_root,field_arg->table);
+      to_field=field_arg->new_field(thd->mem_root,field_arg->table);
       if (to_field)
 	to_field->move_field(ptr, (uchar*) null, 1);
     }