Re: a raft of parallelism-related bug fixes

On 18 February 2016 at 20:35, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>
wrote:

> On Thu, Feb 18, 2016 at 5:35 PM, Amit Langote
> <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> wrote:
> > On 2016/02/18 16:38, Craig Ringer wrote:
> >> I should resurrect Abhijit's patch to allow the isolationtester to talk
> to
> >> multiple servers. We'll want that when we're doing tests like "assert
> that
> >> this change isn't visible on the replica before it becomes visible on
> the
> >> master". (Well, except we violate that one with our funky
> >> synchronous_commit implementation...)
> >
> > How much does (or does not) that overlap with the recovery test suite
> work
> > undertaken by Michael et al? I saw some talk of testing for patches in
> > works on the N synchronous standbys thread.
>
> This sounds like poll_query_until in PostgresNode.pm (already on HEAD)
> where the query used is something on pg_stat_replication for a given
> LSN to see if a standby has reached a given replay position.
>

No, it's quite different, though that's something handy to have that I've
emulated in the isolationtester using a plpgsql function.

The isolationtester changes in question allow isolationtester specs to run
different blocks against different hosts/ports/DBs.

That lets you make assertions about replication behaviour. It was built
for BDR and I think we'll need something along those lines in core if/when
any kind of logical replication facilities land, for things like testing
failover slots, etc.

The patch is at:

http://git.postgresql.org/gitweb/?p=2ndquadrant_bdr.git;a=commit;h=d859de3b13d39d4eddd91f3e6f316a48d31ee0fe

and might be something it's worth having in core as we expand testing of
replication, failover, etc.

--
Craig Ringer http://www.2ndQuadrant.com/
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