From: Valentine Gogichashvili <valgog@gmail.com>
To: andrew@pillette.com <andrew@pillette.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: multicolumn index column order
Date: Tue, 24 Jul 2007 09:40:43 +0200
Message-ID: <3ce9822f0707240040o2f358155p7ff7537bbe986209@mail.gmail.com> (raw)
In-Reply-To: <200707240710.l6O7AUu24090@pillette.com>
References: <200707240710.l6O7AUu24090@pillette.com>
On 7/24/07, andrew@pillette.com <andrew@pillette.com> wrote:
>
> valgog <valgog@gmail.com> wrote ..
> > On Jul 23, 7:00 pm, t...@sss.pgh.pa.us (Tom Lane) wrote:
> > > valgog <val...@gmail.com> writes:
> > > > how to build an multicolumn index with one column order ASCENDING
> and
> > > > another column order DESCENDING?
> > >
> > > Use 8.3 ;-)
> > >
> > > In existing releases you could fake it with a custom reverse-sorting
> > > operator class, but it's a pain in the neck to create one.
>
> I've often gotten what I want by using a calculated index on (f1, -f2).
> ORDER BY will take an expression, e.g. ORDER BY f1, -f2. Simpler than a
> custom operator.
>
Yes, this is true, but I do now know how to make text order be reversible?
There is no - (minus) operator for text value. By now it is not a problem
for me, but theoretically I do not see other chance to reverse text fields
order...
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To: pgsql-performance@postgresql.org
Cc: valgog@gmail.com, andrew@pillette.com
Subject: Re: multicolumn index column order
In-Reply-To: <3ce9822f0707240040o2f358155p7ff7537bbe986209@mail.gmail.com>
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