Re: Proposal for Allow postgresql.conf values to be changed via SQL [review]

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Greg Stark <stark(at)mit(dot)edu>
Cc: Greg Smith <greg(at)2ndquadrant(dot)com>, Amit Kapila <amit(dot)kapila(at)huawei(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, Boszormenyi Zoltan <zb(at)cybertec(dot)at>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Proposal for Allow postgresql.conf values to be changed via SQL [review]
Date: 2013-03-12 16:07:16
Message-ID: 20482.1363104436@sss.pgh.pa.us
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Greg Stark <stark(at)mit(dot)edu> writes:
> As Craig intimated, the minimal grammar impact would be simply

> BEGIN;
> set persistent maintenance_work_mem='2GB';
> set persistent work_mem='2GB';
> COMMIT;

> Sending the sighup at transaction end seems like a fairly safe thing
> to do too. It's hard to imagine it failing and if it did the worst
> case would be that other backends would still have the old values too.

This would only be sane if we also postponed writing the file until
commit. I don't know what is in the patch at the moment, but I remember
that we had talked of executing the file write immediately when SET
PERSISTENT is issued.

Maybe it's worth going in that direction just to cover the
multiple-updates case more conveniently.

regards, tom lane

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