Re: Insert performance with composite index

On Tue, Nov 02, 2010 at 12:04:42PM +0100, Cédric Villemain wrote:
> 2010/11/2 hubert depesz lubaczewski <depesz@depesz.com>:
> > 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;

Best regards,

depesz

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