Re: Postresql 8.0 Beta 3 - SELECT ... FOR UPDATE

Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > Rod Taylor wrote:
> >> Anyway, it shows a situation where it would be nice to differentiate
> >> between statement_timeout and lock_timeout OR it demonstrates that I
> >> should be using userlocks...
>
> > Wouldn't a LOCK NOWAIT be a better solution? That is new in 8.0.
>
> LOCK NOWAIT is only helpful if you can express your problem as not
> wanting to wait for a table-level lock. When you're trying to grab a
> row-level lock via SELECT FOR UPDATE, there isn't any provision for
> NOWAIT.
>
> The notion of a global lock_timeout setting is bogus IMHO, because
> every proposed application of it has failed to consider the locks taken
> internally by the system. But that objection wouldn't apply to a SELECT
> FOR UPDATE NOWAIT command where the "no wait" behavior only applied to
> the row lock being explicitly grabbed.
>
> I thought I remembered someone working on such a thing just recently.

Added to TODO:

* Allow FOR UPDATE queries to do NOWAIT locks

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