Message-ID: <4E9BCB1F.9060208@comodo.com>
Date: Mon, 17 Oct 2011 11:58:47 +0530
From: Robins Tharakan <robins.tharakan@comodo.com>
Organization: Comodo
User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US;
	rv:1.9.2.23) Gecko/20110922 Thunderbird/3.1.15
MIME-Version: 1.0
To: pgsql-performance@postgresql.org
Subject: Bad plan by Planner (Already resolved?)
Content-Type: multipart/signed; protocol="application/pkcs7-signature";
	micalg=sha1; boundary="------------ms070802060004070705040504"

This is a cryptographically signed message in MIME format.

--------------ms070802060004070705040504
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: quoted-printable

Hi,

I stumbled upon a situation where the planner comes with a bad query=20
plan, but I wanted to mention upfront that I'm using a dated PG version=20
and I already see an update which mentions about improving planner=20
performance. I just wanted to check if this issue is already resolved,=20
and if so, which version should I be eyeing.

My PG Version: 8.4.7
Probably solved in: 8.4.8 / 9.0.4 ?

Issue: It seems that the planner is unable to flatten the IN sub-query=20
causing the planner to take a bad plan and take ages (>2500 seconds) and =

expects to give a 100 million row output, where in-fact it should get a=20
six row output. The same IN query, when flattened, PG gives the correct=20
result in a fraction of a second.

Do let me know if this is a new case. I could try to give you the=20
EXPLAIN ANALYSE outputs / approximate table sizes if required.

EXISTING QUERY:
     SELECT field_b FROM large_table_a
         JOIN large_table_b USING (field_b)
     WHERE field_a IN (SELECT large_table_b.field_a
     FROM large_table_b WHERE field_b =3D 2673056)

RECOMMENDED QUERY:
     SELECT s1.field_b FROM large_table_a
         JOIN large_table_b s1 USING (field_b)
         JOIN large_table_b s2 ON s1.field_a =3D s2.field_a
     WHERE s2.field_b =3D 2673056

--
Robins Tharakan


--------------ms070802060004070705040504
Content-Type: application/pkcs7-signature; name="smime.p7s"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="smime.p7s"
Content-Description: S/MIME Cryptographic Signature
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--------------ms070802060004070705040504--