Re: different queries and their efficiencies

David Welton <davidnwelton@gmail.com> writes:
> I'm curious as to what the general opinion is on these different
> queries and their relative merits, especially in terms of speed:

You really should do EXPLAIN ANALYZE rather than assuming that the
planner's estimates are reliable.

The NOT IN case, at least, could be improved by increasing work_mem
to the point where the subquery fits into an in-memory hash table.
Larger work_mem would probably help the sorts used in the other
plans too.

            regards, tom lane