On Tue, Nov 02, 2010 at 12:04:42PM +0100, CÃdric Villemain wrote: > 2010/11/2 hubert depesz lubaczewski <depesz@xxxxxxxxxx>: > > On Mon, Nov 01, 2010 at 02:57:56PM +0100, CÃdric Villemain wrote: > >> > Â CONSTRAINT tableindex_pkey PRIMARY KEY (tableindex) > >> > ) > >> > the index definition is > >> > CREATE INDEX "PK_AT2" > >> > Â ON ABC > >> > Â USING btree > >> > Â (event, tableindex) > >> > TABLESPACE sample; > >> > >> Indexing twice the same column is useless. (perhaps move your PK to > >> the tablespace 'sample' is good too ?) > > > > why do you say that? > > these are not the same indexes and they serve different purposes. > > Given that tableindex is the PK column, I really like to now the usage > pattern for having it indexed twice. select * from table where event = 123 order by tableindex desc limit 50; Best regards, depesz -- Linkedin: http://www.linkedin.com/in/depesz / blog: http://www.depesz.com/ jid/gtalk: depesz@xxxxxxxxxx / aim:depeszhdl / skype:depesz_hdl / gg:6749007 -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
