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

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Magnus Hagander <magnus(at)hagander(dot)net>
Cc: Amit Kapila <amit(dot)kapila(at)huawei(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, Christopher Browne <cbbrowne(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Proposal for Allow postgresql.conf values to be changed via SQL
Date: 2012-11-07 16:53:49
Message-ID: 10478.1352307229@sss.pgh.pa.us
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Magnus Hagander <magnus(at)hagander(dot)net> writes:
> On Wed, Nov 7, 2012 at 5:19 AM, Amit Kapila <amit(dot)kapila(at)huawei(dot)com> wrote:
>> However there is one more point which I am not able to clearly make out is
>> how to write into file that contains
>> all configuration parameters changed by SQL.

> Perhaps you can look at pg_settings, to see if the current setting is
> from the .auto file. If it is, then that's where it came from and it
> should be written back there. If it's something else, that's not where
> it came from.

Note that the whole point of the one-value-per-file approach is to not
have to figure this out.

I'm not sure that the above approach works anyway --- for instance, the
"current setting" might be a SET LOCAL result, in which case you still
don't know anything about what the appropriate thing to put into the
file is. I think there are probably also race conditions with cases
where somebody else just changed some other setting but your session
hasn't absorbed it yet.

regards, tom lane

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