> Hi, > > I have a non-reentrant plperlu function, which does no database > modification. It basically stores input data into a file, calls a unix > shell command, and reads the result back from another file. > > I don't really care about database isolation here, phantom reads and > such. It is not likely to be a problem. What could be a problem, is if > another call to this function is fired while another one is running. > > In this specific case, I could solve the problem by generating random > input and ouput filenames, but I would prefer a more general solution, > like using some sort of mutex for the function. What is the best way to > do that under Postgresql? Although not designed for this (if I > understand correctly), would a "serializable" isolation level help > here? I answer to my own post, sorry... Maybe Postgresql functions "pg_try_advisory_lock_shared" and "pg_advisory_unlock_shared" are the solution? ------------------------------------------------------------- Attik System web : http://www.attiksystem.ch Philippe Lang phone: +41 26 422 13 75 rte de la Fonderie 2 gsm : +41 79 351 49 94 1700 Fribourg pgp : http://keyserver.pgp.com
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