Re: Why is sorting on two columns so slower thansortingon one column?

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Simon Riggs <simon(at)2ndquadrant(dot)com>
Cc: Jie Li <jay23jack(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Kenneth Marshall <ktm(at)rice(dot)edu>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Why is sorting on two columns so slower thansortingon one column?
Date: 2010-12-29 12:15:52
Message-ID: AANLkTim+r8c92DDepkotBe1jgTDPz9c-oeA6V80XbYHw@mail.gmail.com
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers

On Mon, Dec 27, 2010 at 3:58 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> I think the answer is that only the first column comparison is
> optimised. Second and subsequent comparisons are not optimised.

What sort of optimization are you referring to here?

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

In response to

Browse pgsql-hackers by date

  From Date Subject
Next Message Robert Haas 2010-12-29 12:17:17 Re: small table left outer join big table
Previous Message Greg Smith 2010-12-29 12:14:32 Re: new patch of MERGE (merge_204) & a question about duplicated ctid