Re: max_standby_delay considered harmful

Stephen Frost <sfrost@snowman.net>

From: Stephen Frost <sfrost@snowman.net>
To: Simon Riggs <simon@2ndQuadrant.com>
Cc: Stefan Kaltenbrunner <stefan@kaltenbrunner.cc>, Tom Lane <tgl@sss.pgh.pa.us>, pgsql-hackers@postgreSQL.org
Date: 2010-05-03T19:32:46Z
Lists: pgsql-hackers
Simon,

* Simon Riggs (simon@2ndQuadrant.com) wrote:
> Tom's proposed behaviour (has also been proposed before) favours the
> avoid query cancellation route though could lead to huge amounts of lag.

My impression of Tom's suggestion was that it would also be a maximum
amount of delay which would be allowed before killing off queries- not
that it would be able to wait indefinitely until no one is blocking.
Based on that, I don't know that there's really much user-seen behaviour
between the two, except in 'oddball' situations, where there's a time
skew between the servers, or a large lag, etc, in which case I think
Tom's proposal would be more likely what's 'expected', whereas what you
would get with the existing implementation (zero time delay, or far too
much) would be a 'gotcha'..

	Thanks,

		Stephen