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Re: Pushing IN (subquery) down through UNION ALL? - Mailing list pgsql-performance

From Dave Johansen
Subject Re: Pushing IN (subquery) down through UNION ALL?
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Msg-id AANLkTin1mpf=fabt5nvOAnfkBTRR+taVtODTnsKusCn3@mail.gmail.com
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In response to Re: Pushing IN (subquery) down through UNION ALL?  (Vik Reykja <vikreykja@gmail.com>)
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On Thu, Feb 24, 2011 at 12:59 PM, Vik Reykja <vikreykja@gmail.com> wrote:
On Thu, Feb 24, 2011 at 20:56, Dave Johansen <davejohansen@gmail.com> wrote:
On Thu, Feb 24, 2011 at 12:33 PM, Vik Reykja <vikreykja@gmail.com> wrote:
On Thu, Feb 24, 2011 at 16:14, Dave Johansen <davejohansen@gmail.com> wrote:
You'll notice that the subquery version is doing the full join and then the filtering, but the explicitly listed version pushing the filtering into the plan before the join. Is there a way to make the subquery version perform the same optimization?

EXPLAIN ANALYZE SELECT * FROM addressesall WHERE id = ANY (array(SELECT id FROM users WHERE name='A'));

(Tested on 9.0.3)

I just tested that on 8.3.3 and it performed quickly like I expected the other query to, so that did the trick.

Is there any good reason you're not using 8.3.14?

No, I just haven't taken the time to do the upgrade on all of our systems. It is definitely something that I have started to consider more strongly though.

Dave

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