Re: Storing computed values - Mailing list pgsql-general

From Richard Broersma
Subject Re: Storing computed values
Date
Msg-id 396486430804211221y6da92fadi9782b730bb119354@mail.gmail.com
Whole thread Raw
In response to Re: Storing computed values  (Colin Wetherbee <cww@denterprises.org>)
Responses Re: Storing computed values  (Colin Wetherbee <cww@denterprises.org>)
List pgsql-general
On Mon, Apr 21, 2008 at 11:19 AM, Colin Wetherbee <cww@denterprises.org> wrote:

> My impression of functional indexes is that they're useful mostly in WHERE
> queries, like the following.
>
> SELECT foo, bar, baz FROM some_table WHERE lower(foo) = 'qux';
>
> In this case, the index would be created on lower(foo).
>
> How would I get the value of the functional index out of the index in my
> case?

If this is the case, and you use Natural Foreign Keys, you only need
to select from your foo table:

SELECT Connect( location1, location2)
  FROM Foo
 WHERE location1 = ...
        OR location2 = ...
        OR connect(location1,location2) = ...; --this is where the
functional index would be useful


--
Regards,
Richard Broersma Jr.

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