Mike Christensen <mike@xxxxxxxxxxxxx> writes: > When a certain event happens, let's say event 4, I need to query for which > users to notify. So I'll be doing something like: > SELECT UserId FROM Users WHERE Subscriptions & 8; > My question is say there's a million rows in the Users table. If I have an > index on Subscriptions, will this index be used in the above query? No. At least not with a standard btree index. I'm not exactly sure that an index would be helpful at all --- it seems like the selectivity of this condition won't be very good anyway, will it? The more popular notifications will be subscribed to by a large fraction of the user base. Maybe it'd be useful to index unpopular notifications, but how often will you be searching for those? regards, tom lane -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
