On Apr 1, 2006, at 12:51 PM, Brendan Duddridge wrote:
> from SELECT * FROM pg_stats WHERE tablename='table' AND
> attname='category_id'
>
> I find correlation on category_product for category_id is 0.643703
>
> Would setting the index on category_id to be clustered help with this?
It would absolutely help on the query in question. In my experience,
a correlation of 0.64 is too low to allow an index scan to be used
for anything but a tiny number of rows.
--
Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461