| From: | Richard Huxton <dev(at)archonet(dot)com> |
|---|---|
| To: | Luke Lonergan <LLonergan(at)greenplum(dot)com> |
| Cc: | albert(at)sedifa(dot)com, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Posible planner improvement? |
| Date: | 2008-05-21 13:09:49 |
| Message-ID: | 48341F1D.3090304@archonet.com |
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| Lists: | pgsql-hackers pgsql-performance |
Luke Lonergan wrote:
> The problem is that the implied join predicate is not being
> propagated. This is definitely a planner deficiency.
IIRC only equality conditions are propagated and gt, lt, between aren't.
I seem to remember that the argument given was that the cost of
checking for the ability to propagate was too high for the frequency
when it ocurred.
Of course, what was true for code and machines of 5 years ago might not
be so today.
--
Richard Huxton
Archonet Ltd
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