If I have this:
create table foo (bar int primary key);
...then in my ideal world, Postgres would be able to use that index on bar
to help me with this:
select bar from foo order by bar desc limit 20;
But in my experience, PG8.2 is doing a full table scan on foo, then
sorting it, then doing the limit. I have a more complex primary key, but I
was hoping the same concept would still apply. Am I doing something wrong,
or just expecting something that doesn't exist?