On 10 May 2010, at 24:01, Christoph Zwerschke wrote: > We want to find all entries in b where txt begins with an > existing txt entry in a: > > select * from b join a on b.txt like a.txt||'%' > > On the first glance you would expect that this is performant > since it can use the index, but sadly it doesn't work. > The problem seems to be that Postgres can not guarantee that > column a.txt does not contain a '%', so it cannot optimize. > > I feel there should be a performat way to query these entries, > but I can't come up with anything. Can anybody help me? Have you tried using substring instead of like? Alban Hertroys -- If you can't see the forest for the trees, cut the trees and you'll see there is no forest. !DSPAM:737,4be7d6ec10411051620847! -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
