Why is the query not using the index for sorting? - Mailing list pgsql-performance

From Jonathan Blitz
Subject Why is the query not using the index for sorting?
Date
Msg-id 6913EA33EE934FF3B17ADA8A87082D15@jblaptop
Whole thread Raw
Responses Re: Why is the query not using the index for sorting?  (Thom Brown <thombrown@gmail.com>)
Re: Why is the query not using the index for sorting?  (Craig Ringer <craig@postnewspapers.com.au>)
Re: Why is the query not using the index for sorting?  (Matthew Wakeling <matthew@flymine.org>)
List pgsql-performance
I have a table with a number of columns.
 
I perform
 
Select *
from table
order by a,b
 
There is an index on a,b which is clustered (as well as indexes on a and b alone).
I have issued the cluster and anyalze commands.
 
Nevertheless, PostgreSQL performs a Sequential Scan on the table and then performs a sort.
Am I missing something?
 
Jonathan Blitz

pgsql-performance by date:

Previous
From: afancy
Date:
Subject: Re: Performance degrade running on multicore computer
Next
From: Thom Brown
Date:
Subject: Re: Why is the query not using the index for sorting?