From: | Philippe Girolami <philippe(dot)girolami(at)sensorly(dot)com> |
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To: | "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: Push predicate down in view containing window function |
Date: | 2013-11-15 06:43:53 |
Message-ID: | 0dfniv0mh4w3fch9o8doytdn.1384497808896@email.android.com |
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Lists: | pgsql-general |
Ok so is there a way i can do something similar ? Would a function returning rows and taking the extra predicate 'values' as parameters be as optimized as the 'good' query in my first email ?
Thanks.
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> a écrit :
Philippe Girolami <philippe(dot)girolami(at)sensorly(dot)com> writes:
> Hello,
> Using postgres 9.1.9, I have a view that uses a window function. I then query that view with a predicate on one of the columns. Unfortunately, the predicate doesn't get pushed down into the view.
> Given that the predicate applies to a column that's being partitionned on, why wouldn't the optimizer push the predicate down ?
Because there is zero optimization around window functions right now.
It certainly isn't smart enough to decide that it'd be safe to push
down a constraint that only mentions partitioning columns.
regards, tom lane
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