Re: pg_standby -l might destory the archived file

Aidan Van Dyk wrote:
> * Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> [090601 10:56]:
>> Tom Lane wrote:
>>> Fujii Masao <masao(dot)fujii(at)gmail(dot)com> writes:
>>>> pg_standby can use ln command to restore an archived file,
>>>> which might destroy the archived file as follows.
>>> Does it matter? pg_standby's source area wouldn't normally be an
>>> "archive" in the real sense of the word, it's just a temporary staging
>>> area between master and slave. (If it were being used as a real
>>> archive, keeping it on the same disk as the live slave seems pretty
>>> foolish anyway, so the case wouldn't arise.)
>> It seems perfectly sane to source pg_standby directly from the archive
>> to me. And we're talking about symbolic linking, so the archive
>> directory might well be on an NFS mount.
>
> I would expect that any archive directly available would at least be RO
> to the postgres slave... But....

Me too.

I wonder if we should just remove the symlink option from pg_standby.
Does anyone use it? Is there a meaningful performance difference?

> Something like this would stop the "symlink" being renamed... Not portable, but probably portable
> across platforms that have symlinks...
> diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c

That seems reasonable as well.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com