On Jan 26, 2010, at 9:41 AM, Richard Neill wrote: > Thanks for your answers. > > > David Wilson wrote: > >> Why not simply add the where clause to the original query? >> >> SELECT >> SUM (case when id > 1200000 and id < 1210000 then 1 else 0 end) AS c1, >> SUM (case when id > 1210000 and id < 1220000 then 1 else 0 end) AS c2, >> SUM (case when id > 1220000 and id < 1230000 then 1 else 0 end) AS c3, >> SUM (case when id > 1230000 and id < 1240000 then 1 else 0 end) AS c4, >> SUM (case when id > 1240000 and id < 1250000 then 1 else 0 end) AS c5 >> FROM tbl_tracker WHERE (id>1200000) AND (id<1250000); >> >> I didn't populate any test tables, but I'd expect that to do just as >> well without being any uglier than the original query is. > > You're absolutely right, but I'm afraid this won't help. I'd simplified > the original example query, but in real life, I've got about 50 > different sub-ranges, which cover virtually all the id-space. >
Well, it probably shouldn't use the index if it covers the vast majority of the table. I wonder if it is actually faster to reformulate with WHERE or not at that point -- it might be slower. -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
