Forcing the use of one index instead other.

You could remove the index numberfail.

PG can use the index failtype in the case you just need a where clause
on numberfail also....

Ries

Hello there!

I have two index with a same field into them like this:

create index numberfail on Events (numberfail);
and
create index failtype on Events (numberfail,eventtype);

then i ran explain analyze and always took the numberfail index
but i wish the failtype index;

this is the query:

SELECT * FROM events WHERE numberfail=194 AND eventtype='XXX';

What should i to do to force the use of failtypeindex????

I though maybe if i delete the index numberfail could works, but i
don't know if the another program
will fail if the numberfail index does'nt exists.

well, thats all for the moment and i appreciate your time in reading
this mail!!!
See you.
--
SENSA Control Digital.
Ing. Edmundo Robles Lopez.
Analista Programador.

regards, Ries van Twisk

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Ries van Twisk
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"Edmundo Robles L." <erobles@sensacd.com.mx> writes:

I have two index with a same field into them like this:

create index numberfail on Events (numberfail);
and
create index failtype on Events (numberfail,eventtype);

then i ran explain analyze and always took the numberfail index but

i wish the failtype index;

Uh, why? If you have the smaller index available it's hard to imagine
any sane reason not to use it.

I though maybe if i delete the index numberfail could works, but i don't know if the another program
will fail if the numberfail index does'nt exists.

No, you can drop that one if you want to. You might care to read the
fine manual about index design:
http://www.postgresql.org/docs/8.3/static/indexes.html

regards, tom lane