Re: Insert performance with composite index

2010/11/2 hubert depesz lubaczewski <depesz(at)depesz(dot)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.

>
> Best regards,
>
> depesz
>
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Cédric Villemain               2ndQuadrant
http://2ndQuadrant.fr/     PostgreSQL : Expertise, Formation et Support