Last inserted row id in PostgreSQL

I am using postgresql database. And previous tables which are created by my seniors and they are not used sequence concept, they added data manually. Now i need to insert data with my java application. for that i need last inserted ID. I have no permission to add sequence开发者_如何转开发.

please anybody help me.

thanks in advance...

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You'd ideally ask for permission to create the needed sequences.

If it's not an option for some bureaucratic reason you might manage to work around concurrency issues using advisory locks. Pseudo-code:

loop
select id as last_id, pg_try_advisory_lock('yourtable'::regclass, id) as locked
from yourtable
order by id desc limit 1

 if not locked then sleep .01 else exit end if
end loop

new_id = last_id + 1
insert...

select pg_advisory_unlock('yourtable'::regclass, last_id)