Thanks guys for your suggestions, but the problem turned out to be my
lack of experience(with PostgreSQL), combined with a bug in our PHP
Code.
Coming from a MySQL background, I assumed that if you "select x from
y", then y would be the name of a table. It turned out that in the
case that y was actually a view. It has a complex defination, but for
explanitory sake, lets say it was defined as:
select u.username, g.groupname from users u, groups g where u.group_id=g.id
(assuming users are in exactly one group)
If the group_id field in the users table was corrupted, and set to a
value that isn't in the groups table, then that view wouldn't return
anything.
Something like that(except that our view wasn't quite as simple) happened to me.
