Re: Connections hang indefinitely while taking a gin index's LWLock buffer_content lock

On Wed, Dec 12, 2018 at 4:08 PM Andrey Borodin <x4mmm(at)yandex-team(dot)ru> wrote:
> > 12 дек. 2018 г., в 3:26, Alexander Korotkov <aekorotkov(at)gmail(dot)com> написал(а):
> >
> > BTW, I still can't see you're setting deleteXid field of
> > ginxlogDeletePage struct anywhere.
> Oops. Fixed.
> >
> > Also, I note that protection against re-usage of recently deleted
> > pages is implemented differently than it is in B-tree.
> > 1) You check TransactionIdPrecedes(GinPageGetDeleteXid(page),
> > RecentGlobalDataXmin)), while B-tree checks
> > TransactionIdPrecedes(opaque->btpo.xact, RecentGlobalXmin). Could you
> > clarify why do we use RecentGlobalDataXmin instead of RecentGlobalXmin
> > here?
> As far as I understand RecentGlobalDataXmin may be slightly farther than RecentGlobalXmin in case when replication_slot_catalog_xmin is holding RecentGlobalXmin. And GIN is never used by catalog tables. But let's use RecentGlobalXmin like in B-tree.
>
> > 2) B-tree checks this condition both before putting page into FSM and
> > after getting page from FSM. You're checking only after getting page
> > from FSM. Approach of B-tree looks better for me. It's seems more
> > consistent when FSM pages are really free for usage.
> Fixed.

Thank you. I've revised your patch and pushed it. As long as two
other patches in this thread.

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company