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Message-ID: <f966c2ee0803220208p3b47585bg788139a4a7e85bd7@mail.gmail.com>
Date: Sat, 22 Mar 2008 14:38:25 +0530
From: "sathiya psql" <sathiya.psql@gmail.com>
To: "Craig Ringer" <craig@postnewspapers.com.au>
Subject: Re: Having MANY MANY empty columns in database
Cc: pgsql-performance@postgresql.org
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>
> OK, so your tables all have the same fields (columns), as if you used
> CREATE TABLE new_table ( LIKE some_template_table ) ?


It will contain some other unique columns for each table.

> meaning that they contain NULL values in that field for every record?


what is the  value it may contain i don't know ?? we are not filling any
value !!

>
> > If you drop those columns we will gain any performance or not.....
>
 I need to test... HOW to test the overall performance of database..

> However, I recall hearing that PostgreSQL keeps a null bitmap and doesn't
> use any storage for null fields. If that is correct then you probably won't
> be paying much of a price in disk I/O, but there might still be other costs.
>
if it is sure that it will not make disk I/O then it is ok

>
> I can't help wondering why you have all those useless columns in the
> first place, and why you have so many identically structured tables.
>
these are not useless columns... it should be used to update the owner of
the record, updated time, created and other stuffs, but nobody is using now.


>
> --
> Craig Ringer
>

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<div class="gmail_quote"><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">OK, so your tables all have the same fields (columns), as if you used<br>

CREATE TABLE new_table ( LIKE some_template_table ) ?</blockquote><div><br>It will contain some other unique columns for each table. <br>
</div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">meaning that they contain NULL values in that field for every record?</blockquote><div>
&nbsp;</div><div>what is the&nbsp; value it may contain i don&#39;t know ?? we are not filling any value !!<br>
</div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div class="Ih2E3d"><br>
&gt; If you drop those columns we will gain any performance or not.....</div></blockquote><div>&nbsp;I need to test... HOW to test the overall performance of database..<br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">

However, I recall hearing that PostgreSQL keeps a null bitmap and doesn&#39;t use any storage for null fields. If that is correct then you probably won&#39;t be paying much of a price in disk I/O, but there might still be other costs.<br>

</blockquote><div>if it is sure that it will not make disk I/O then it is ok <br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><br>

I can&#39;t help wondering why you have all those useless columns in the<br>
first place, and why you have so many identically structured tables.<br>
</blockquote><div>these are not useless columns... it should be used to update the owner of the record, updated time, created and other stuffs, but nobody is using now. <br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<br>
--<br>
<font color="#888888">Craig Ringer<br>
</font></blockquote></div><br>

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