Re: SEVEN cross joins?!?!? - Mailing list pgsql-sql

From Stewart Ben (RBAU/EQS4) *
Subject Re: SEVEN cross joins?!?!?
Date
Msg-id E253BDD7F008244585AEE87AF8F0224F116C7ACB@cl-mail01.au.bosch.com
Whole thread Raw
In response to SEVEN cross joins?!?!?  (Frank Bax <fbax@sympatico.ca>)
List pgsql-sql
> Splitting locations into subsets (like 2,2,3) doesn't work
> because it is possible that low values in one location can be offset
by
> high values in another location, and still result in an excellent
combo.
>
> The good news is these suggestions got me thinking outside
> the box.  I think I can program a modified brute-force that bypasses
> large numbers of combos early.  It might still be too large/slow, so
I'd be
> interested in finding more info about these "smarter algorithms" in
option

Could you define an view with a calculated field, say, 2 * a1 + 6 * a2 +
3 * a3, and then use this aggregate to score the individual rows? I
haven't looked at the exact nature of the problem, but if you're
multiplying a table by itself, it may be worth redefining the problem in
terms of a simple ranking algorithm, define a column to calculate this,
then sort by that column.

Best regards,

Ben Stewart

--
Robert Bosch (Australia) Pty. Ltd.
Engineering Quality Services, Student Software Engineer (RBAU/EQS4)
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Tel: +61 3 9541-7002 Fax: +61 3 9541-7700
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