From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | sailesh(at)cs(dot)berkeley(dot)edu, Jenny - <nat_lazy(at)hotmail(dot)com>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: this is in plain text (row level locks) |
Date: | 2003-07-24 05:21:53 |
Message-ID: | 200307240521.h6O5LrG02796@candle.pha.pa.us |
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Lists: | pgsql-hackers |
Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > Tom Lane wrote:
> >> This is actually an issue though. Row-level shared locks would be
> >> really nice to have for foreign-key handling. Right now we have to
> >> use X locks for those, and that leads to deadlocking problems for
> >> applications.
>
> > Is the plan to allow one backend to shared lock the row while others can
> > read it but not modify it, or is the idea to actually allow multiple
> > backends to record their shared status on the row?
>
> Plan? We have no plan to fix this :-(. But clearly there has to be
> some way to tell which backends hold read locks on a shared-locked row,
> else you can't tell if they've all dropped the lock or not.
I suppose we could allow one backend to mark the page with a shared lock
for primary key purposes while others read it. Does that buy us
anything?
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073
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