From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
Cc: | pgsql-hackers(at)postgreSQL(dot)org |
Subject: | Re: Strange locking choices in pg_shdepend.c |
Date: | 2008-01-21 23:06:30 |
Message-ID: | 21626.1200956790@sss.pgh.pa.us |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
Alvaro Herrera <alvherre(at)commandprompt(dot)com> writes:
> Tom Lane wrote:
>> Why does shdepDropOwned() take AccessExclusiveLock on pg_shdepend?
> Hmm, I can't recall nor deduce any reason for that. Perhaps the
> intention was to protect against itself; but I think this should only
> matter if we're dropping the same role concurrently (otherwise the
> to-be-dropped objects would be disjoint sets, so it doesn't matter),
> which should be already protected by the lock on the role itself.
> Hmm, unless revoking privileges concurrently, for two different users on
> the same object could cause a problem? I don't see us grabbing a lock
> on the object itself -- does this matter?
Well, if there is any such problem then it could be triggered by two
independent plain-ol-REVOKE commands, so I still don't see an argument
why shdepDropOwned is more at risk than anything else. I think we
should just downgrade the lock.
regards, tom lane
From | Date | Subject | |
---|---|---|---|
Next Message | Larry Rosenman | 2008-01-21 23:29:51 | Makefile support for Mac OS X Fat Binaries? |
Previous Message | Tom Lane | 2008-01-21 23:03:29 | Re: [GENERAL] setof record "out" syntax and returning records |