Re: bzr commit into mysql-5.0-bugteam branch (gshchepa:2662) Bug#37894

[Sergey Petrunia]

On Thu, Oct 02, 2008 at 03:20:31PM +0200, Sergei Golubchik wrote:
> Hi, Sergey!
> 
> On Oct 02, Sergey Petrunia wrote:
> > Hi!
> > 
> > On Sat, Sep 20, 2008 at 02:16:15AM +0500, Gleb Shchepa wrote:
> > > #At file:///work/bzr/5.0-bugteam-37894/
> > > 
> > >  2662 Gleb Shchepa	2008-09-20
> > >       Bug #37894: Assertion in init_read_record_seq in handler.h
> > >       line 1444
> > >       
> > >       Select with a "NULL NOT IN" condition containing complex
> > >       subselect from the same table as in the outer select failed
> > >       with an assertion.
> > 
> > More, I believe that there is no need to have additional handler
> > object at all. It should be easy to examine handler->inited,
> > handler->active_index, save their state and restore it at the end of
> > the scan, please do so.  (If it's not that trivial then I'm missing
> > something, please let me know).
> 
> You cannot easily save the state of the handler, as you have no access
> to it. Most of the state is inside the storage engine, probably spead
> over different (internal to the storage engine) structures.

And we don't need any of that for this bug, because

* the scan will be restarted (so, there's no need, e.g. to save index scan
  position).

* we aren't making arbitrary changes. We just switch to full table scan,
  then switch back.

BR
 Sergey
-- 
Sergey Petrunia, Lead Software Engineer
MySQL AB, www.mysql.com
Office: N/A
Blog: http://s.petrunia.net/blog