Re: Why is this doing a seq scan?

Hmm.  Have you VACUUM ANALYZED the tables?  If so, what do you get from
these queries:

select attname,attdisbursion,s.*
from pg_statistic s, pg_attribute a, pg_class c
where starelid = c.oid and attrelid = c.oid and staattnum = attnum
and relname = 'zips';

select attname,attdisbursion,s.*
from pg_statistic s, pg_attribute a, pg_class c
where starelid = c.oid and attrelid = c.oid and staattnum = attnum
and relname = 'atms';

Also it would be useful to see the full declarations of the tables
and their indexes; I'm wondering what datatype the zip columns are,
for example.
        regards, tom lane