Re: incrementing updates and locks

On 09/16/2010 10:54 PM, Aras Angelo wrote:
> Hello All
>
> I have a column in my table which is incrementally updated. I cant set
> this field to be a SERIAL because the value is not assigned at the
> time of the INSERT, it is assigned later by the system by an UPDATE.
> Whats the best way to achieve this by means of performance?

It sounds like what you need is a sequence.
http://www.postgresql.org/docs/8.3/static/sql-createsequence.html

There is one gotcha - if you obtain a value from the sequence, and the
transaction is rolled back, the value is *not* reissued; so, you could
get gaps. If that's unacceptable, you might try indexing that field; I
don't know if max uses them, but it'd be worth a try.

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