-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Strk, you're so on the money! :) Thank you very much! The query now runs in ~40ms :P
I also wish to thank everyone gracious enough to have shared their thoughts. BR, Pedro Doria Meunier GSM: +351 96 17 20 188 Skype: pdoriam strk wrote: > On Fri, Jun 12, 2009 at 10:54:11AM +0100, Pedro Doria Meunier > wrote: >> -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 >> >> Thank you Strk. >> >> The actual query is as thus: >> >> select astext(st_centroid(st_collect(coordinates))) from units >> where customer_id=someid >> >> So there's a 'where' clause in it :] > > The 'where' clause specifies a condition on the 'customer_id' > field. The only index the planner might use would be on on that > column. Have an index there (looks like the analizer already thinks > it'd be worth using, estimating only 9 rows selectivity for that > clause, where 4 are returned in reality) > > --strk; > >> EXPLAIN ANALYZE tells me: >> >> "Aggregate (cost=49790.11..49790.13 rows=1 width=25) (actual >> time=524.380..524.381 rows=1 loops=1)" " -> Seq Scan on units >> (cost=0.00..49790.09 rows=9 width=25) (actual >> time=445.782..524.231 rows=4 loops=1)" " Filter: >> (customer_id = 20)" "Total runtime: 524.451 ms" >> >> The runtime is a bit stiff, don't you agree? ;-) > > Probably. How many rows does the table have ? > > --strk; > > Free GIS & Flash consultant/developer () ASCII Ribbon > Campaign http://foo.keybit.net/~strk/services.html /\ Keep it > simple! _______________________________________________ > postgis-users mailing list [email protected] > http://postgis.refractions.net/mailman/listinfo/postgis-users > -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (GNU/Linux) Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org iD8DBQFKMivR2FH5GXCfxAsRAtjiAKCdjtMYlFsbeYQAISiTlp8wa7ueUACguQPb 1KTz2rJOKR4xOnxaEvjj/Ro= =9QOL -----END PGP SIGNATURE----- _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
