Horton

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

Alexander Korotkov <aekorotkov@gmail.com>

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From: Alexander Korotkov <aekorotkov@gmail.com>
To: Andrey Borodin <x4mmm@yandex-team.ru>
Cc: Peter Geoghegan <pg@bowt.ie>, Andres Freund <andres@anarazel.de>, chenhj <chjischj@163.com>, Teodor Sigaev <teodor@sigaev.ru>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2018-12-10T22:43:42Z
Lists: pgsql-hackers 
On Mon, Dec 10, 2018 at 4:58 PM Andrey Borodin <x4mmm@yandex-team.ru> wrote:
> > 10 дек. 2018 г., в 18:56, Andrey Borodin <x4mmm@yandex-team.ru> написал(а):
> >
> > PFA this part. In thread about GiST vacuum Heikki was not very happy with reusing PageHeader->pd_prune_xid for this. But we somewhat concluded that this might be OK.
> > Anyway, there's whole page, we can store those bits anywhere.

We might allocate special field in opaque to store stat xid like
B-tree or SP-GiST.  But we have to be binary compatible.  And this
change shouldn't require upgrade procedure, since we're going to
backpatch that.  We could allocate space elsewhere on the page, but
that would be a bit cumbersome.  So, let's use pd_prune_xid once it's
available.

> Errrmm... I'm very sorry for the noise. I've forgot the actual patch.

Attached patch appears to be incomplete.  GinPageSetDeleteXid() is
called only in ginRedoDeletePage(), so only in recovery, while it
should be set during normal work too.  deleteXid field of
ginxlogDeletePage is never set.

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

Commits

  1. Fix WAL format incompatibility introduced by backpatching of 52ac6cd2d0

  2. Fix wrong backpatching of ginRedoDeletePage() deadlock fix

  3. Fix deadlock in GIN vacuum introduced by 218f51584d5

  4. Prevent GIN deleted pages from being reclaimed too early

  5. Prevent deadlock in ginRedoDeletePage()

  6. Reduce page locking in GIN vacuum

  7. Fix race condition in GIN posting tree page deletion.