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To: "Ross J. Reedstrom" <reedstrm@wallace.ece.rice.edu>
cc: Gary Stainburn <gary.stainburn@ringways.co.uk>,
	"'Pgsql Interfaces'" <pgsql-interfaces@postgreSQL.org>
Subject: Re: [INTERFACES] locking on database updates 
In-reply-to: Your message of Tue, 7 Dec 1999 11:12:34 -0600
	<19991207111234.A6021@rice.edu>
Date: Tue, 07 Dec 1999 12:59:33 -0500
Message-ID: <23996.944589573@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

"Ross J. Reedstrom" <reedstrm@wallace.ece.rice.edu> writes:
> create table foo (bar serial, baz text);
> insert into foo (baz) values ('wooble');
> select currval('foo_bar_seq');

I don't think this is safe in a multi-client environment;
what if someone else inserts at about the same time?

Better to do
	select nextval('foo_bar_seq');
	insert into foo values (just-retrieved-value, 'wooble');
which is safer and probably marginally faster (since the
sequence object is touched only once, not twice).

			regards, tom lane