On 9 January 2012 19:45, Josh Berkus <j...@agliodbs.com> wrote: >> Obviously, many indexes are unique and thus won't have duplicates at >> all. But if someone creates an index and doesn't make it unique, odds >> are very high that it has some duplicates. Not sure how many we >> typically expect to see, but more than zero... > > Peter may not, but I personally admin lots of databases which have > indexes on values like "category" or "city" which have 100's or 1000's > of duplicates per value. I don't think this is uncommon at all.
Uh, then all the more reason to do what I recommend, I imagine. There is most definitely a large overhead to creating such indexes, at least for scalar types. As far as I can tell, Tom's complaint is quite speculative. -- Peter Geoghegan http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training and Services -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers