Re: Referencing serial col's sequence for insert

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От David G Johnston
Тема Re: Referencing serial col's sequence for insert
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Msg-id 1406039082942-5812382.post@n5.nabble.com
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Ответ на Re: Referencing serial col's sequence for insert  (Albe Laurenz <laurenz.albe@wien.gv.at>)
Ответы Re: Referencing serial col's sequence for insert  (Albe Laurenz <laurenz.albe@wien.gv.at>)
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Albe Laurenz *EXTERN* wrote
> Also, I think that your method is vulnerable to race conditions:
> If somebody else increments the sequence between the INSERT and
> "SELECT lastval()" you'd get a wrong value.

Uh, no.  It returns that last value issued in the same session - which is
race-proof.

http://www.postgresql.org/docs/9.3/static/functions-sequence.html

Both of them are useful and in the case of inserting multiple rows you have
to use RETURNING.  Beyond though it is largely personal preference and
ease-of-use (dealing with a set when you know a single value is all that is
necessary can be annoying).

David J.



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