Re: multicolumn index column order
| От | Valentine Gogichashvili |
|---|---|
| Тема | Re: multicolumn index column order |
| Дата | |
| Msg-id | 3ce9822f0707240040o2f358155p7ff7537bbe986209@mail.gmail.com обсуждение исходный текст |
| Ответ на | multicolumn index column order (valgog <valgog@gmail.com>) |
| Список | pgsql-performance |
On 7/24/07, andrew@pillette.com <andrew@pillette.com> wrote:
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...
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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