Re: Indexes with descending date columns - Mailing list pgsql-performance

From Theo Kramer
Subject Re: Indexes with descending date columns
Date
Msg-id 1143174749.2820.2.camel@josh
Whole thread Raw
In response to Re: Indexes with descending date columns  (andrew@pillette.com)
Responses Re: Indexes with descending date columns  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-performance
On Thu, 2006-03-23 at 16:16, Alvaro Herrera wrote:
> Theo Kramer wrote:
>
> > All good input - thanks, however, before I start messing with my stuff
> > which I know will be complex - some questions to any of the developers
> > on the list.
> >
> > i  Is it feasible to extend index creation to support descending
> >    columns? ... this is supported on other commercial and non
> >    commercial databases, but I do not know if this is a SQL standard.
>
> This can be done.  You need to create an operator class which specifies
> the reverse sort order (i.e. reverse the operators), and then use it in
> the new index.

Hmmm, would that then result in the following syntax  being valid?

  create index my_idx on my_table (c1, c2 desc, c3, c4 desc) ;

where my_table is defined as

  create table my_table (
    c1 text,
    c2 timestamp,
    c3 integer,
    c4 integer
  );

If so, I would appreciate any pointers on where to start on this -
already fumbling my way through Interfacing Extensions To Indexes in the
manual...

Regards
Theo
--
Regards
Theo


pgsql-performance by date:

Previous
From: Christopher Browne
Date:
Subject: Re: Scaling up PostgreSQL in Multiple CPU / Dual Core
Next
From: Tom Lane
Date:
Subject: Re: Indexes with descending date columns