Hyun-Sang,
> before test, I already executed VACUUM FULL.
> this result show up after vacuum full.
Really? Your results really look like a bloated table. Can you run VACUUM
FULL ANALYZE VERBOSE on the table and post the output?
> When I using index scan, the result was almost same, that means, there
> was no time difference, so i'll not mention about index scan.
Can we see an index scan plan anyway? EXPLAIN ANALYZE?
Oh, and if this is a zip codes table, why are you using a sequence as the
primary key instead of just using the zip code?
--
Josh Berkus
Aglio Database Solutions
San Francisco