Re: Hot standby, slot ids and stuff

From: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
To: Simon Riggs <simon(at)2ndQuadrant(dot)com>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Hot standby, slot ids and stuff
Date: 2009-01-08 20:31:28
Message-ID: 496662A0.5080801@enterprisedb.com
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Simon Riggs wrote:
> * if FATAL errors occur, yet we have long running transactions then we
> have no way of removing those entries from the recovery procs. Since we
> have a fixed pool of recovery transactions we won't have anywhere to
> store that data. Snapshot sizes are fixed maximum with max_connections,
> so eventually we would not be able to take a snapshot at all, and we'd
> need to have a "ERROR: unable to take valid snapshot".

When a backend dies with FATAL, it writes an abort record before exiting.

(I was under the impression it doesn't until few minutes ago myself,
when I actually read the shutdown code :-))

> * if FATAL errors occur while holding AccessExclusiveLock then we have
> no way of releasing those locks until the recovery proc is stale, which
> might be some time. Not sure if your patch releases those?

I don't think so, that needs to be fixed.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com

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