| From: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Boxuan Zhai <bxzhai2010(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: gSoC add MERGE command new patch -- merge_v104 |
| Date: | 2010-08-25 06:26:51 |
| Message-ID: | 4C74B7AB.7010307@enterprisedb.com |
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| Thread: | |
| Lists: | pgsql-hackers |
On 24/08/10 23:56, Andres Freund wrote:
> I have to ask one question: On a short review of the discussion and
> the patch I didn't find anything about the concurrency issues
> involved (at least nodeModifyTable.c didnt show any).
The SQL spec doesn't require MERGE to be an atomic "upsert" operation.
> Whats the plan to go forward at that subject? I think the patch needs
> to lock tables exclusively (the pg level, not access exclusive) as
> long as there is no additional handling...
Well, you can always do LOCK TABLE before calling MERGE if that's what
you want, but I don't think doing that automatically would make people
happy.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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