From: | Frank Bax <fbax(at)sympatico(dot)ca> |
---|---|
To: | |
Cc: | pgsql-novice(at)postgresql(dot)org |
Subject: | Re: select records by nearest value |
Date: | 2011-05-14 12:27:33 |
Message-ID: | 4DCE7535.9060908@sympatico.ca |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-novice |
On 05/14/11 06:49, e-letter wrote:
> Readers,
>
> A database is structured as follows:
>
> 1 text1
> 1000 text2
> 500 text3
>
> where column 1 consists of integers. Is it possible to create query
> that will select the most appropriate records for a sum of integers.
> For example, if the target sum of integers is 50, is it possible to
> select a set of records that will be closest to this value?
I think your question is a variation of the "nearest neighbour" problem.
I found this page useful, even though I do not use PostGIS.
http://www.bostongis.com/PrinterFriendly.aspx?content_name=postgis_nearest_neighbor
In your case the "distance" function might be as simple as
"ABS(id - 50)"
where "id" is the first column in your sample table above.
From | Date | Subject | |
---|---|---|---|
Next Message | Joshua Tolley | 2011-05-14 13:44:04 | Re: More WAL archiving/backup questions |
Previous Message | e-letter | 2011-05-14 10:49:16 | select records by nearest value |