type of index?

I'm wondering about the types of indexes available. I have an indexed
column in a table which will ONLY be used with the '=' operator - in
other words:

SELECT foo FROM bar WHERE this_col = 1234;

Should the index on this_col be a btree or a hash index? By default, it
seems like Postgres is creating a btree index. But according to the
PgSQL docs, a hash index could also be used. Which would result in
better performance? Also, I've read in the list archives that
btree indexes are much better, in general, than the others. Given this,
which index is the best? Is there some of rule of thumb I can use
to decide for this and other cases?

Thanks in advance,

Neil

--
Neil Conway <neilconway(at)home(dot)com>
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