On Thu, 31 Jul 2003 11:06:09 -0400, "Jianshuo Niu" <[EMAIL PROTECTED]> wrote: >I ran the same explain analyze on two similar tables. However, the table >with less data took much more time than the one with more data. Could anyone >tell me what happened?
>Seq Scan on tfd_catalog (cost=0.00..43769.82 rows=161282 width=10) (actual >time=3928.64..12905.76 rows=161282 loops=1) >Total runtime: 13240.21 msec > >Seq Scan on hm_catalog (cost=0.00..22181.18 rows=277518 width=9) (actual >time=21.32..6420.76 rows=277518 loops=1) >Total runtime: 6772.95 msec The first SELECT takes almost twice the time because tfd_catalog has almost twice as many pages than hm_catalog. This may be due to having wider tuples or more dead tuples in tfd_catalog. In the former case theres not much you can do. But the high startup cost of the first SELECT is a hint for lots of dead tuples. So VACUUM FULL ANALYSE might help. Servus Manfred ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faqs/FAQ.html