From: | Hiroshi Inoue <inoue(at)tpf(dot)co(dot)jp> |
---|---|
To: | Richard Huxton <dev(at)archonet(dot)com> |
Cc: | Heikki Linnakangas <heikki(at)enterprisedb(dot)com>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Concurrently updating an updatable view |
Date: | 2007-05-14 21:13:09 |
Message-ID: | 4648D0E5.5020608@tpf.co.jp |
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Lists: | pgsql-hackers |
Richard Huxton wrote:
> Heikki Linnakangas wrote:
>> The problem is that the new tuple version is checked only against the
>> condition in the update rule, id=OLD.id, but not the condition in the
>> original update-claus, dt='a'.
>>
>> Yeah, that's confusing :(.
>
> Bit more than just normal rule confusion I'd say. Try the following two
> statements in parallel (assuming you've just run the previous):
>
> UPDATE test SET dt='c';
> UPDATE test SET dt='x' FROM test t2 WHERE test.id=t2.id AND t2.dt='b';
>
> This isn't a problem with the view mechanism - it's a problem with
> re-checking clauses involving subqueries or joins I'd guess.
I don't understand the PostgreSQL specific *FROM* clause correctly.
Currently the relations in the *FROM* clause seem to be read only
and UPDATE operations seem to acquire no tuple level lock on them.
regards,
Hiroshi Inoue
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