2010/11/2 hubert depesz lubaczewski <depesz@xxxxxxxxxx>: > On Tue, Nov 02, 2010 at 12:04:42PM +0100, Cédric Villemain wrote: >> 2010/11/2 hubert depesz lubaczewski <depesz@xxxxxxxxxx>: >> > On Mon, Nov 01, 2010 at 02:57:56PM +0100, Cédric Villemain wrote: >> >> > CONSTRAINT tableindex_pkey PRIMARY KEY (tableindex) >> >> > ) >> >> > the index definition is >> >> > CREATE INDEX "PK_AT2" >> >> > ON ABC >> >> > USING btree >> >> > (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; Correct. Thanks Hubert. -- Cédric Villemain 2ndQuadrant http://2ndQuadrant.fr/ ; PostgreSQL : Expertise, Formation et Support -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
