Re: MEDIAN as custom aggregate? - Mailing list pgsql-sql

"Josh Berkus" <josh@agliodbs.com> writes:
> The query I'll use is this:

> SELECT site, COUNT(pageviews) as count_views, AVG(pageviews) AS
> mean_views, median_views
> FROM sites, 
>     (SELECT pageviews as median_view
>      FROM pageviews
>      LIMIT 1 OFFSET middlerec('pageviews')) med
> GROUP BY site, median_views;

> Where middlerec is a custom function that counts the records and returns
> the middle one.

Um ... does that work?  I thought LIMIT was fairly restrictive about
what it would take as a parameter --- like, constants or $n parameters
only.

I do not know of any median-finding algorithm that doesn't require a
depressingly large amount of storage...
        regards, tom lane