Shane Wright wrote:
> Hi
>
> I'm having trouble getting my head round postgres's locking. I've read
> through all the docs but cant seem to find the right thingthat does what I
> want...
>
>
> Basically, there are a few tables in my system where a SELECT is done prior
> to an INSERT to avoid duplicating certain data and so forth.
>
> So, I want to lock the table for the transaction that does the stuff above so
> no more than one can run at a time (essentially making it SERIALIZABLE).
> But, I dont want to block other readers from SELECTing from the table at the
> same time...
>
> This is the classic multiple readers, single writer problem yes? I'm sure
> its doable, but I cant work out which locking / transaction isolation levels
> to use.
See my chapter on transactions. I think you want SERIALIZABLE
transaction mode.
http://www.postgresql.org/docs/awbook.html
-- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610)
853-3000+ If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill,
Pennsylvania19026
