Tnks Qingqing, I've read them! Nevertheless I think there are some differences here: * The difference in the amout of rows is much smaller. Nevertheless the table is small as well: only 100 rows * There is a faster query plan to solve the query: "Bitmap Heap Scan on hosts (cost=2.07..11.34 rows=21 width=59) (actual time=0.175..0.287 rows=21 loops=1)" " Recheck Cond: ((hostname)::text = 'Fabian'::text)" " -> Bitmap Index Scan on hosts_hostname (cost=0.00..2.07 rows=21 width=0) (actual time=0.145..0.145 rows=21 loops=1)" " Index Cond: ((hostname)::text = 'Fabian'::text)" "Total runtime: 0.510 ms" This result was achieved by setting enable_seqscan to off (postgresql.conf). Turning off enable_bitmapscan as well resulted in a index scan which was even more faster: "Index Scan using hosts_hostname on hosts (cost=0.00..37.28 rows=21 width=59) (actual time=0.068..0.281 rows=21 loops=1)" " Index Cond: ((hostname)::text = 'Fabian'::text)" "Total runtime: 0.492 ms" Yours, Aarjan ----- Original Message ----- From: "Qingqing Zhou" <zhouqq@xxxxxxxxxxxxxx> To: <pgsql-general@xxxxxxxxxxxxxx> Sent: Tuesday, November 22, 2005 12:38 AM Subject: Re: [GENERAL] Difference in indexes > > ""A.j. Langereis"" <a.j.langereis@xxxxxxxxxxxx> wrote > > > > What is happening here? What am I overlooking? The length does not > > seem to be the problem: 'FooFooFoo' also uses the index.. > > Also the fact whenever there are results or not does not seem to > > influence the planner.. > > > > Check out this thread: > > http://archives.postgresql.org/pgsql-bugs/2005-11/msg00032.php > > Regards, > Qingqing > > > > ---------------------------(end of broadcast)--------------------------- > TIP 6: explain analyze is your friend > >
