| Lists: | pgsql-general |
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| From: | "Marc Mamin" <M(dot)Mamin(at)intershop(dot)de> |
|---|---|
| To: | <pgsql-general(at)postgresql(dot)org> |
| Subject: | Question on STABLE functions limitations |
| Date: | 2010-10-18 08:47:30 |
| Message-ID: | C4DAC901169B624F933534A26ED7DF31034BB838@JENMAIL01.ad.intershop.net |
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| Lists: | pgsql-general |
Hello,
I wonder if there are some special cases where STABLE functions should
be avoided.
I think for example of functions using set_config or querying the
advisory locks.
Thanks in advance,
Marc Mamin
| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "Marc Mamin" <M(dot)Mamin(at)intershop(dot)de> |
| Cc: | pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Question on STABLE functions limitations |
| Date: | 2010-10-18 14:18:28 |
| Message-ID: | 19012.1287411508@sss.pgh.pa.us |
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| Lists: | pgsql-general |
"Marc Mamin" <M(dot)Mamin(at)intershop(dot)de> writes:
> I wonder if there are some special cases where STABLE functions should
> be avoided.
> I think for example of functions using set_config or querying the
> advisory locks.
set_config has side-effects and hence should not be done in non-volatile
functions.
regards, tom lane
| From: | Merlin Moncure <mmoncure(at)gmail(dot)com> |
|---|---|
| To: | Marc Mamin <M(dot)Mamin(at)intershop(dot)de> |
| Cc: | pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Question on STABLE functions limitations |
| Date: | 2010-10-18 14:30:53 |
| Message-ID: | AANLkTi=r2RH6S+Boqg0t9Mvqj66DBa3fpiwBXyx9BbOA@mail.gmail.com |
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| Lists: | pgsql-general |
On Mon, Oct 18, 2010 at 4:47 AM, Marc Mamin <M(dot)Mamin(at)intershop(dot)de> wrote:
> I wonder if there are some special cases where STABLE functions should be
> avoided.
>
> I think for example of functions using set_config or querying the advisory
> locks.
Advisory locks are highly volatile and everything that touches them
should be considered volatile. They are completely outside the mvcc
snapshot system and aren't bound by its rules (sequences also fall
under this category).
merlin