Re: Statistical Analysis - Mailing list pgsql-general

From Timothy H. Keitt
Subject Re: Statistical Analysis
Date
Msg-id 397CB5C2.10441378@nceas.ucsb.edu
Whole thread Raw
In response to RE: Statistical Analysis  ("Nathan Barnett" <nbarnett@cellularphones.com>)
Responses Re: Statistical Analysis
Re: Statistical Analysis
List pgsql-general
Oops.  Just tried that; the random() call only get evaluated once.  What
you need is a column type "random" that calls random() each time its
evaluted.

T.

Andrew McMillan wrote:
>
> Nathan Barnett wrote:
> >
> > Stephan,
> >         The SORT is what I'm trying to avoid because I was using a group by to grab
> > all the data in the groups that I needed, but it requires a sort to group by
> > and this bottlenecked the query.  I really just wanted to grab a sample of
> > all the rows in the table and then perform the group by on the subset to
> > avoid the overhead of sorting the whole table.  My query has no where
> > clauses and thus must sort through all of the data being analyzed.  It then
> > aggregates the data in a table that is then being used in the realtime
> > queries.  The analysis must be able to run every hour.
>
> What about using random() in the WHERE clause?
>
> Regards,
>                                 Andrew.
> --
> _____________________________________________________________________
>             Andrew McMillan, e-mail: Andrew@cat-it.co.nz
> Catalyst IT Ltd, PO Box 10-225, Level 22, 105 The Terrace, Wellington
> Me: +64 (21) 635 694, Fax: +64 (4) 499 5596, Office: +64 (4) 499 2267

--
Timothy H. Keitt
National Center for Ecological Analysis and Synthesis
735 State Street, Suite 300, Santa Barbara, CA 93101
Phone: 805-892-2519, FAX: 805-892-2510
http://www.nceas.ucsb.edu/~keitt/

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