On 9/22/06, AgentM <[EMAIL PROTECTED]> wrote:
> Except you can put tables (and pretty much all your other objects)
> in a
> schema, one that's presumably named after your application. That
> greatly
> removes the odds of conficts.

Indeed. In our development environment, we store development,
integration, and testing schemas in the same database. This makes it
trivial to move testing data to development, for example.

If I want to use these locks, it seems I will have to hard-code some
offset into each app or hash the schema name and use that as an
offset :( In any case, I can't imagine the "wtf?" nightmares an
accidental collision would induce.

i think you are obsuring something here.  advisory_lock is a mutex
with a numeric name...thats it :) any meaning you impart into that
name is your problem.  listen/notify is a similar construct in that

I ran an erp system, one company per schema, using userlock module for
pessimistic row locking with no problems.  I used bit shifting to
strip off the high bit (out of 48) for special table locks and other
things.  key mechasim was to use a sequence to provide lock id which
was shared by all lockable objects. a domain could be appropriate

create sequence lock_provider;
create domain lockval as bigint default nextval('lock_provider');

and the following becomes standard practice:
create table foo (lv lockval);  <--no need for index here
select pg_advisory_lock(lv) from foo where [..];

for bit shifting or special cases you can wrap the lock function, which i did.


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