Skip site navigation (1)
Skip section navigation (2)
Peripheral Links
Header And Logo
|
Site Navigation
Re: Why date index is not used
- From: "Jim C. Nasby" <jnasby(at)pervasive(dot)com>
- To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
- Cc: Andrus <eetasoft(at)online(dot)ee>, pgsql-performance(at)postgresql(dot)org
- Subject: Re: Why date index is not used
- Date: Thu, 8 Jun 2006 16:57:45 -0500
On Thu, Jun 08, 2006 at 03:20:55PM -0400, Tom Lane wrote: > "Andrus" <eetasoft(at)online(dot)ee> writes: > > Why Postgres 8.1 does not use makse_kuupaev_idx index in the following query > > ? > > Because it doesn't help --- the system still has to do the sort. > You'd need a two-column index on both of the ORDER BY columns to avoid > sorting. And even then you better have a pretty high correlation on the first column, otherwise you'll still get a seqscan. -- Jim C. Nasby, Sr. Engineering Consultant jnasby(at)pervasive(dot)com Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
- Follow-Ups:
- Re: Why date index is not used
- From: Tom Lane
- Re: Why date index is not used
- References:
- Why date index is not used
- From: Andrus
- Re: Why date index is not used
- From: Tom Lane
- Why date index is not used
- Prev by Date: Re: Why date index is not used
- Next by Date: Re: Why date index is not used
- Previous by thread: Re: Why date index is not used
- Next by thread: Re: Why date index is not used
- Indexes: