Re: max_standby_delay considered harmful

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Simon Riggs <simon(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: max_standby_delay considered harmful
Date: 2010-05-06 00:29:52
Message-ID: 201005060029.o460Tqp02775@momjian.us
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Robert Haas wrote:
> >> If you have the monitoring in place to sensibly monitor the delay
> >> between primary and standby, and you want a limit on that, you can put
> >> together a script to flip the switch in postgresql.conf if the standby
> >> falls too much behind.
> >>
> >> It would be nice to make that settable per-session, BTW. Though as soon
> >> as you have one session using -1, the standby could fall behind. Still,
> >> it might be useful if you run both kinds of queries on the same standby.
> >
> > +1 for a boolean
> >
> > We are not supposed to be designing the behavior during beta, which is
> > exactly what we are doing, and I don't think we even know what behavior
> > we want, let alone have we implemented it. ?I think a boolean is very
> > clear and it gives you the chance to optimize _one_ case, which is
> > enough for 9.0. ?Let's revisit this for 9.1 when we will know a lot more
> > than we do now.
>
> The existing behavior is probably not optimal, but I'm not seeing what
> benefit we get out of neutering it.

We get to design it right, or maybe not need it at all in 9.1.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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