Received: from maia.hub.org (maia-3.hub.org [200.46.204.243])
	by mail.postgresql.org (Postfix) with ESMTP id 60D9D1337B68
	for <pgsql-performance-postgresql.org@mail.postgresql.org>;
	Wed, 23 Mar 2011 04:25:29 -0300 (ADT)
Received: from mail.postgresql.org ([200.46.204.86])
	by maia.hub.org (mx1.hub.org [200.46.204.243]) (amavisd-maia,
	port 10024) with ESMTP id 14938-03
	for <pgsql-performance-postgresql.org@mail.postgresql.org>;
	Wed, 23 Mar 2011 07:25:17 +0000 (UTC)
X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6
Received: from mail-fx0-f46.google.com (mail-fx0-f46.google.com
	[209.85.161.46])
	by mail.postgresql.org (Postfix) with ESMTP id 200DE13364DE
	for <pgsql-performance@postgresql.org>;
	Wed, 23 Mar 2011 04:25:16 -0300 (ADT)
Received: by fxm17 with SMTP id 17so7080382fxm.19
	for <pgsql-performance@postgresql.org>;
	Wed, 23 Mar 2011 00:25:16 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma;
	h=domainkey-signature:message-id:date:from:user-agent:mime-version:to
	:subject:references:in-reply-to:content-type;
	bh=m8wgGTXoJOA/dBI+i7Hb3DR7I4SnBzsssxi+Yu4YRBY=;
	b=EUF6SN7Nhbh3hRg/smGIMMzbar6v9u7qxcS7mJO/nrIzSiBxHBo6RDExbYeNl78KJT
	RqVgoM5b9eucPf7fsbFMj0et+TLURmqbVMvtc7vRSQF7Lkmr88truzaT8BVbKK7YvYiW
	9lQ7sJYax37SDmAC4nW3qQt5GWNF2AVa8jutE=
DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma;
	h=message-id:date:from:user-agent:mime-version:to:subject:references
	:in-reply-to:content-type;
	b=ERC+Ik9DFo2aUkuwaXcEfNesEmgTOH/W+bt/Np4P65NrahaC71eL4+n7XGLqgRlCSF
	l5BGQKWAUQFjE6uH0hJWubSMPsSoZyTGjTrrGor0joscj6cdWJq8Jb2V2tI0l3BdOABy
	A2nbfPZhuyMbi/ARqMxf9Rj4XEPpUANlz6WAM=
Received: by 10.223.15.141 with SMTP id k13mr2639186faa.30.1300865116100;
	Wed, 23 Mar 2011 00:25:16 -0700 (PDT)
Received: from [10.1.1.57] (skuns.zoral.com.ua [91.193.166.194])
	by mx.google.com with ESMTPS id f15sm3276052fax.34.2011.03.23.00.25.14
	(version=TLSv1/SSLv3 cipher=OTHER);
	Wed, 23 Mar 2011 00:25:15 -0700 (PDT)
Message-ID: <4D89A06E.2020202@gmail.com>
Date: Wed, 23 Mar 2011 09:25:34 +0200
From: Vitalii Tymchyshyn <tivv00@gmail.com>
User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US;
	rv:1.9.2.14) Gecko/20110223 Lightning/1.0b2 Thunderbird/3.1.8
MIME-Version: 1.0
To: pgsql-performance@postgresql.org
Subject: Re: Reason of Slowness of query
References: <4D899301.7070301@orkash.com>
In-Reply-To: <4D899301.7070301@orkash.com>
Content-Type: multipart/alternative;
	boundary="------------000001010109050006030700"
X-Virus-Scanned: Maia Mailguard 1.0.1
X-Spam-Status: No, hits=-1.035 tagged_above=-10 required=5
	tests=BAYES_00=-1.9, FREEMAIL_ENVFROM_END_DIGIT=1.553,
	FREEMAIL_FROM=0.001,
	HTML_MESSAGE=0.001, RCVD_IN_DNSWL_LOW=-0.7, T_TO_NO_BRKTS_FREEMAIL=0.01
X-Spam-Level: 
X-Archive-Number: 201103/256
X-Sequence-Number: 42935

This is a multi-part message in MIME format.
--------------000001010109050006030700
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit

23.03.11 08:28, Adarsh Sharma ???????(??):
> *
> *I perform a join query on it as :
>
> * explain analyze select distinct(p.crawled_page_id) from page_content 
> p , clause2  c where p.crawled_page_id != c.source_id ;*
Your query is wrong. This query will return every *crawled_page_id* if 
clause2 has more then 1 source_id. This is because DB will be able to 
find clause with source_id different from crawled_page_id. You need to 
use "not exists" or "not in".

Best regards, Vitalii Tymchyshyn.

--------------000001010109050006030700
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <meta content="text/html; charset=ISO-8859-1"
      http-equiv="Content-Type">
  </head>
  <body bgcolor="#ffffff" text="#000000">
    23.03.11 08:28, Adarsh Sharma &#1085;&#1072;&#1087;&#1080;&#1089;&#1072;&#1074;(&#1083;&#1072;):
    <blockquote cite="mid:4D899301.7070301@orkash.com" type="cite">
      <b><br>
      </b>I perform a join query on it as :<br>
      <br>
      <b>&nbsp;explain analyze select distinct(p.crawled_page_id) from
        page_content p , clause2&nbsp; c where p.crawled_page_id !=
        c.source_id ;</b><br>
    </blockquote>
    Your query is wrong. This query will return every <b>crawled_page_id</b>
    if clause2 has more then 1 source_id. This is because DB will be
    able to find clause with source_id different from crawled_page_id.
    You need to use "not exists" or "not in".<br>
    <br>
    Best regards, Vitalii Tymchyshyn.<br>
  </body>
</html>

--------------000001010109050006030700--