Re: Strang behaviour SELECT ... LIMIT n FOR UPDATE

"Daniel Caune" <daniel.caune@ubisoft.com> writes:
> I'm facing a strange behaviour with a statement SELECT ... LIMIT n FOR
> UPDATE in PostgreSQL 8.1.  The number of rows returned is actually (n -
> 1).  I'm trying to find whether this is an identified issue with
> PostgreSQL 8.1 that might have been fixed in a later version such as
> 8.2; I don't have any problem in moving to a later version if needed.

There's no known issue specifically of that form (and a quick test of
8.1 doesn't reproduce any such behavior).  However, it is known and
documented that LIMIT and FOR UPDATE behave rather oddly together:
the LIMIT is applied first, which means that if FOR UPDATE rejects
any rows as being no longer up-to-date, you get fewer than the expected
number of rows out.  You did not mention any concurrent activity in
your example, but I'm betting there was some ...
        regards, tom lane