Re: Support for N synchronous standby servers - take 2

From: Michael Paquier <michael(dot)paquier(at)gmail(dot)com>
To: kharagesuraj <suraj(dot)kharage(at)nttdata(dot)com>
Cc: PostgreSQL mailing lists <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Support for N synchronous standby servers - take 2
Date: 2016-02-09 04:15:15
Message-ID: CAB7nPqRfx9YFnKT1T0TP5AvKTaECwr+WST2y0bNox91O1n_rxQ@mail.gmail.com
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On Tue, Feb 9, 2016 at 12:16 PM, kharagesuraj <suraj(dot)kharage(at)nttdata(dot)com>
wrote:

> Hello,
>
>
>
>
>
> >> I agree with first version, and attached the updated *patch* which are
> >> modified so that it supports simple multiple sync replication you
> >>suggested.
> >> (but test cases are not included yet.)
>
>
>
> I have tried for some basic in-built test cases for multisync rep.
>
> I have created one patch over Michael's <a href="
> http://www.postgresql.org/message-id/CAB7nPqTEqou=[hidden email]
> <http:///user/SendEmail.jtp?type=node&node=5886503&i=0>">patch</a> patch.
>
> Still it is in progress.
>
> Please have look and correct me if i am wrong and suggest remaining test
> cases.
>

So the interesting part of this patch is 006_sync_rep.pl. I think that you
had better build something on top of my patch as a separate patch. This
would make things clearer.

+my $result = $node_master->psql('postgres', "select application_name,
sync_state from pg_stat_replication;");
+print "$result \n";
+is($result, "standby_1|sync\nstandby_2|sync\nstandby_3|potential",
'checked for sync standbys state initially');
Now regarding the test, you visibly got the idea, though I think that we'd
want to update a bit the parameters of postgresql.conf and re-run those
queries a couple of times, that's cheaper than having to re-create new
cluster nodes all the time, so just create a base, then switch s_s_names a
bit, and query pg_stat_replication, and you are already doing the latter.

Also, please attach patches directly to your emails. When loading something
on nabble this is located only there and not within postgresql.org which
would be annoying if nabble disappears at some point. You would also want
to use directly an email client and interact with the community mailing
lists this way instead of going through the nabble's forum-like interface
(never used it, not really willing to use it, but I guess that it is
similar to that).

I am attaching what you posted on this email for the archive's sake.
--
Michael

Attachment Content-Type Size
recovery_test_suite_with_multisync.patch application/x-download 26.7 KB

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