From: Laurenz Albe <laurenz.albe@cybertec.at>
To: danydb@noalyss.eu
To: pgsql-docs@lists.postgresql.org
Subject: Re: SET feature
Date: Fri, 28 Oct 2022 13:59:08 +0200
Message-ID: <7fac2a589357d64cb249b057ddb91d7e747722c9.camel@cybertec.at> (raw)
In-Reply-To: <166695204625.630.3067402447013848509@wrigleys.postgresql.org>
References: <166695204625.630.3067402447013848509@wrigleys.postgresql.org>
On Fri, 2022-10-28 at 10:14 +0000, PG Doc comments form wrote:
> I remember in version 9 , to use variable you had to change in the
> postgresql.
>
> Today it is easier , just use
>
> SET SESSION myprefix.myvariable = 'whatever'
>
> and all the transactions can use it , it is very useful in some cases, for
> example to track the author of a change , you don't need to change all your
> java/php/python code , just use a trigger on the table to fill up a column
> "change_by"
>
> I've checked the documentation and that feature is not explained at all, not
> even in the SET Command.
Most people consider this a kind of abuse of what is known as "placeholder parameters",
documented in https://www.postgresql.org/docs/current/runtime-config-custom.html
See for example https://postgr.es/m/2982579.1662416866%40sss.pgh.pa.us
I believe it is a deliberate choice not to advertise that as "session variables",
particularly since there is an improvement in the pipeline:
https://commitfest.postgresql.org/40/1608/
Yours,
Laurenz Albe
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To: pgsql-docs@postgresql.org
Cc: laurenz.albe@cybertec.at, danydb@noalyss.eu, pgsql-docs@lists.postgresql.org
Subject: Re: SET feature
In-Reply-To: <7fac2a589357d64cb249b057ddb91d7e747722c9.camel@cybertec.at>
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