Horton

Re: snapbuild woes

Andres Freund <andres@anarazel.de>

View thread View on postgr.es
From: Andres Freund <andres@anarazel.de>
To: Petr Jelinek <petr.jelinek@2ndquadrant.com>
Cc: Noah Misch <noah@leadboat.com>, pgsql-hackers@postgresql.org, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, Erik Rijkers <er@xs4all.nl>, David Steele <david@pgmasters.net>, Robert Haas <robertmhaas@gmail.com>, Craig Ringer <craig@2ndquadrant.com>, pgsql-hackers-owner@postgresql.org
Date: 2017-05-15T03:31:31Z
Lists: pgsql-hackers 
On 2017-05-14 14:54:37 +0200, Petr Jelinek wrote:
> On 13/05/17 22:23, Andres Freund wrote:
> >> And wait for session 3 to finish slot creation, takes about 20 mins on
> >> my laptop without patches, minute and half with your patches for 0004
> >> and 0005 (or with your 0004 and my 0005) and about 2s with my original
> >> 0004 and 0005.
> > 
> > Is that with assertions enabled or not?  With assertions all the time
> > post patches seems to be spent in some Asserts in reorderbuffer.c,
> > without it takes less than a second for me here.
> >
> 
> Right you are, I always forget to switch that off before benchmarks.

Phew ;)

> > I'm appylying these now.
> 
> Cool. Just for posterity, this also fixes the issue number 3 as the
> switch to consistent state is done purely based on xl_running_xacts and
> not decoded commits/aborts.

Cool.  Although I'm still not convinced, as noted somewhere in this
thread, that it actually did much to start with ;)

Greetings,

Andres Freund

Commits

  1. Fix thinko introduced in 2bef06d516460 et al.

  2. Avoid superfluous work for commits during logical slot creation.

  3. Fix race condition leading to hanging logical slot creation.

  4. Don't use on-disk snapshots for exported logical decoding snapshot.

  5. Preserve required !catalog tuples while computing initial decoding snapshot.