| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Jaime Casanova <systemguards(at)gmail(dot)com> |
| Cc: | Rick Gigger <rick(at)alpinenetworking(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>, "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>, josh(at)agliodbs(dot)com, pgsql-hackers(at)postgresql(dot)org, Peter Eisentraut <peter_e(at)gmx(dot)net> |
| Subject: | Re: MERGE vs REPLACE |
| Date: | 2005-11-16 17:12:10 |
| Message-ID: | 200511161712.jAGHCAj22465@candle.pha.pa.us |
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| Lists: | pgsql-hackers |
Jaime Casanova wrote:
> On 11/16/05, Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> wrote:
> >
> > Interesting approach. Actually, we could tell the user they have to use
> > BEGIN;LOCK tab before doing MERGE, and throw an error if we don't
> > already have a table lock.
> >
>
> If the lock will be required, what's the problem in doing it
> internally? without user interaction?
Because first, we are making it visible to the user, and second the lock
is taken out _before_ we actually execute the statement, meaning we
don't have to escalate our locks.
--
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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