| From: | "Tsunakawa, Takayuki" <tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com> |
|---|---|
| To: | 'Robert Haas' <robertmhaas(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Bruce Momjian <bruce(at)momjian(dot)us>, Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, Gavin Flower <GavinFlower(at)archidevsys(dot)co(dot)nz>, "Ideriha, Takeshi" <ideriha(dot)takeshi(at)jp(dot)fujitsu(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, Andres Freund <andres(at)anarazel(dot)de>, "Michael Paquier" <michael(dot)paquier(at)gmail(dot)com>, David Steele <david(at)pgmasters(dot)net>, Craig Ringer <craig(at)2ndquadrant(dot)com> |
| Subject: | RE: Protect syscache from bloating with negative cache entries |
| Date: | 2019-01-25 07:26:46 |
| Message-ID: | 0A3221C70F24FB45833433255569204D1FB70E6B@G01JPEXMBYT05 |
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| Lists: | pgsql-hackers |
From: Robert Haas [mailto:robertmhaas(at)gmail(dot)com]
> On Thu, Jan 24, 2019 at 10:02 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > I will argue hard that we should not do it at all, ever.
> >
> > There is already a mechanism for broadcasting global GUC changes:
> > apply them to postgresql.conf (or use ALTER SYSTEM) and SIGHUP.
> > I do not think we need something that can remotely change a GUC's
> > value in just one session. The potential for bugs, misuse, and
> > just plain confusion is enormous, and the advantage seems minimal.
>
> I think there might be some merit in being able to activate debugging
> or tracing facilities for a particular session remotely, but designing
> something that will do that sort of thing well seems like a very
> complex problem that certainly should not be sandwiched into another
> patch that is mostly about something else. And if we ever get such a
> thing I suspect it should be entirely separate from the GUC system.
+1 for a separate patch for remote session configuration. ALTER SYSTEM + SIGHUP targeted at a particular backend would do if the DBA can log into the database server (so, it can't be used for DBaaS.) It would be useful to have pg_reload_conf(pid).
Regards
Takayuki Tsunakawa
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