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Message-ID: <4D89C926.8050009@orkash.com>
Date: Wed, 23 Mar 2011 15:49:18 +0530
From: Adarsh Sharma <adarsh.sharma@orkash.com>
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To: Vitalii Tymchyshyn <tivv00@gmail.com>
CC: pgsql-performance@postgresql.org
Subject: Re: Re-Reason of Slowness of Query
References: <4D89BABF.4080806@orkash.com> <4D89BCD6.6040604@gmail.com>
	<4D89C704.5080603@orkash.com> <4D89C778.6050805@gmail.com>
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Vitalii Tymchyshyn wrote:
> 23.03.11 12:10, Adarsh Sharma ???????(??):
>> I just want to retrieve that id 's from page_content which do not 
>> have any entry in clause2 table.
>>
> Then
> select distinct(p.crawled_page_id) from page_content p
>  where NOT EXISTS (select 1 from  clause2 c where c.source_id = 
> p.crawled_page_id);
> is correct query.
>

I can't understand how* select 1 from  clause2 c where c.source_id = 
p.crawled_page_id works too, *i get my output .

What is the significance of 1 here.

Thanks , Adarsh
**
> Best regards, Vitalii Tymchyshyn.


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Vitalii Tymchyshyn wrote:
<blockquote cite="mid:4D89C778.6050805@gmail.com" type="cite">
  <meta content="text/html; charset=ISO-8859-1"
 http-equiv="Content-Type">
23.03.11 12:10, Adarsh Sharma &#1085;&#1072;&#1087;&#1080;&#1089;&#1072;&#1074;(&#1083;&#1072;):
  <blockquote cite="mid:4D89C704.5080603@orkash.com" type="cite">
    <meta content="text/html; charset=ISO-8859-1"
 http-equiv="Content-Type">
I just want to retrieve that id 's from page_content which do not have
any entry in clause2 table.<br>
    <br>
  </blockquote>
Then <br>
select distinct(p.crawled_page_id) from page_content p<br>
&nbsp;where NOT EXISTS (select 1 from&nbsp; clause2 c where c.source_id =
p.crawled_page_id);<br>
is correct query.<br>
  <br>
</blockquote>
<br>
I can't understand how<b> select 1 from&nbsp; clause2 c where c.source_id =
p.crawled_page_id works too, </b>i get my output .<br>
<br>
What is the significance of 1 here.<br>
<br>
Thanks , Adarsh<br>
<b></b>
<blockquote cite="mid:4D89C778.6050805@gmail.com" type="cite"> Best
regards, Vitalii Tymchyshyn.<br>
</blockquote>
<br>
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