From: Jim Nasby [mailto:jnasby@xxxxxxxxxxxxx]
Sent: Fri 6/16/2006 1:49 AM
To: surabhi.ahuja
Cc: Michael Fuhr; pgsql-general@xxxxxxxxxxxxxx
Subject: Re: [GENERAL] B+ versus hash maps
On Jun 15, 2006, at 8:07 AM, surabhi.ahuja wrote:
> is
there any way of specifying wht type of index i want, say hash
>
maps instead of the B+ trees.
> someone told me that in the case where
duplicates occur(on the
> indexed field), hash map are better than
B+ trees.
http://www.postgresql.org/docs/8.1/interactive/sql-createindex.html
>
and also please tell if i can assume that it will use index only
>
and not go for sequential scan,
> again i was told for that i ll have to
set the random page cost
> parameter to 1.
The database will
use whatever it thinks is optimal. Use explain
analyze to see what it's
doing.
Unless your database fits (and stays) entirely in memory,
you'll
probably be pretty unhappy with random_page_cost=1.
--
Jim
C. Nasby, Sr. Engineering Consultant
jnasby@xxxxxxxxxxxxx
Pervasive Software http://pervasive.com work:
512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf
cell: 512-569-9461
