On Wed, Jun 07, 2006 at 09:34:47AM +0800, Qingqing Zhou wrote:
>
> "Qingqing Zhou" <zhouqq@cs.toronto.edu> wrote
> >
> > The overall performance improvement might be marginal but why not if it is
> > right. What I cares is the correctness. As I understand, the orginal code
> > puts a shared lock (1) to prevent the vacuum process to move tuples around
> > so the hint bits change may happen in a wrong place; (2) to prevent other
> > operations holding EXCLUSIVE lock to change bits at the same time.
> >
>
> I realized I made an aweful mistake. The shared lock also (3) to prevent
> other operations holding EXCLUSIVE lock to change the xid fields at the
> same. So the final conclusion is: the original code is right and my patch is
> terriblly wrong :-(
Maybe a comment patch would be in order to prevent future confusion?
--
Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461