> 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?
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