Date: Tue, 3 Nov 2015 16:43:00 +0100
From: Andres Freund <andres@anarazel.de>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Jeff Janes <jeff.janes@gmail.com>,
 "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: Re: BUG #13685: Archiving while idle every
 archive_timeout with wal_level hot_standby
Message-ID: <20151103154300.GY11897@awork2.anarazel.de>
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On 2015-11-03 10:23:35 -0500, Robert Haas wrote:
> On Mon, Nov 2, 2015 at 12:58 AM, Jeff Janes <jeff.janes@gmail.com> wrote:
> > If a transaction holding locks aborts on an otherwise idle server, perhaps it will take a very long time for a log-shipping standby to realize this.  But I have hard time believing that anyone who cares about that would be using log-shipping (rather than streaming) anyway.
> 
> I'm sure other people here understand this better than me, but I
> wonder if it wouldn't make more sense to somehow log this data only if
> something material has changed in the data being logged.

Phew. That doesn't seem easy to measure. I'm doubtful that it's worth
comparing the snapshot and such, especially in the back
branches.

We could maybe add something that we only log a snapshot if XXX
megabytes have been logged or something. But I don't know which number
to pick here - and if there's other write activity the price of a
snapshot record really isn't high.

Andres


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