Hi there,
I just noticed a little optimizer problem - in second query there is
unused 'tycho t2' table alias which gets backend buried. This is
artificial query, I just tried to check if optimizier could recognize
this.
tycho=# explain analyze select t.pm_ra,t.pm_dec from tycho t where t.pm_ra < 20.2 and t.pm_ra> 18;
QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------------
IndexScan using pm_ra_idx on tycho t (cost=0.00..9821.83 rows=2613 width=8) (actual time=0.061..12.518 rows=1466
loops=1) Index Cond: ((pm_ra < 20.2::double precision) AND (pm_ra > 18::double precision)) Total runtime: 14.726 ms
(3 rows)
tycho=# explain analyze select t.pm_ra,t.pm_dec from tycho t, tycho t2 where t.pm_ra < 20.2 and t.pm_ra> 18;
...........................................
It's doing Nested Loop, probably, so I didn' wait until it completed....
Regards, Oleg
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83
