mlw writes:
> update mytable set foo=foo+1 where bar='xxx';
>
> If that gets executed more than once at the same time by multiple instances of
> postgresql. Will foo ever lose a count?
No, but if you run this in read committed isolation mode then you might
get into non-repeatable read type problems, i.e., you run it twice but
every foo was only increased once. If you use serializable mode then all
but one concurrent update will be aborted.
--
Peter Eisentraut peter_e@gmx.net