From: Dmitry Lenev
Date: October 1 2010 4:01pm
Subject: Re: bzr commit into mysql-5.5-runtime branch (jon.hauglid:3146)
	Bug#51099
List-Archive: http://lists.mysql.com/commits/119706
Message-Id: <20101001160112.GB19481@mockturtle>
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Hello Jon Olav!

* Jon Olav Hauglid <jon.hauglid@stripped> [10/09/27 19:38]:
> #At file:///export/home/x/mysql-5.5-runtime-bug51099/ based on revid:jon.hauglid@stripped
> 
>  3146 Jon Olav Hauglid	2010-09-27
>       Bug #51099 Assertion in mysql_multi_delete_prepare()
>       
>       This assert was triggered if DELETE was done on a view that
>       referenced another view which in turn (directly or indirectly)
>       referenced more than one table.
>       
>       Delete from a view referencing more than one table (a join view)
>       is not supported and is supposed to give ER_VIEW_DELETE_MERGE_VIEW
>       error. Before this error was reported from the multi table 
>       delete code, an assert verified that the view from the DELETE statement
>       had more than one underlying table. However, this assert did not take
>       into account that the view could refer to another view which in turn
>       referenced the actual tables.
>       
>       This patch fixes the problem by adjusting the assert to only verify
>       that we are trying to insert into a view, rather than also try to verify
>       there are more than one underlying table.
>       
>       This problem was only noticeable on debug builds of the server.
>       On release builds, ER_VIEW_DELETE_MERGE_VIEW was correctly reported.

...

> === modified file 'sql/sql_delete.cc'
> --- a/sql/sql_delete.cc	2010-07-28 11:17:19 +0000
> +++ b/sql/sql_delete.cc	2010-09-27 15:25:26 +0000
> @@ -524,10 +524,7 @@ int mysql_multi_delete_prepare(THD *thd)
>    {
>      if (!(target_tbl->table= target_tbl->correspondent_table->table))
>      {
> -      DBUG_ASSERT(target_tbl->correspondent_table->view &&
> -                  target_tbl->correspondent_table->merge_underlying_list &&
> -                  target_tbl->correspondent_table->merge_underlying_list->
> -                  next_local);
> +      DBUG_ASSERT(target_tbl->correspondent_table->view);

Maybe it makes sense to preserve original intent behind the assert by
adjusting it in the following way:

DBUG_ASSERT(target_tbl->correspondent_table->view &&
            target_tbl->correspondent_table->multitable_view);

What do you think?

>        my_error(ER_VIEW_DELETE_MERGE_VIEW, MYF(0),
>                 target_tbl->correspondent_table->view_db.str,
>                 target_tbl->correspondent_table->view_name.str);
> 

I think it is OK to push this fix after considering the above suggestion.

-- 
Dmitry Lenev, Software Developer
Oracle Development SPB/MySQL, www.mysql.com

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