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From: Nikolas Everett <nik9000@gmail.com>
To: raghavendra t <raagavendra.rao@gmail.com>
Cc: Matthew Wakeling <matthew@flymine.org>
Cc: Tadipathri Raghu <traghu.dba@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Jeremy Harris <jgh@wizmail.org>
Cc: pgsql-performance@postgresql.org
Subject: Re: Optimizer showing wrong rows in plan
Date: Mon, 29 Mar 2010 09:43:18 -0400
Message-ID: <d4e11e981003290643s42bcdd68reab7006bbb3eaba6@mail.gmail.com> (raw)
In-Reply-To: <bc7de5a31003290524k42878045ree4ef4f0333731e7@mail.gmail.com>
References: <645d9d71003272351x766707c7sadde9aa77bc1c0d3@mail.gmail.com>
	<645d9d71003280011q6cf2c6d6p7279605e6e0b4235@mail.gmail.com>
	<e4edc9361003280029v7174f84bo72d073aced772206@mail.gmail.com>
	<645d9d71003280033l16069edcp45d9bbb0e7ed5517@mail.gmail.com>
	<22618.1269793661@sss.pgh.pa.us>
	<4BAF8D1D.2050109@wizmail.org>
	<24446.1269797854@sss.pgh.pa.us>
	<645d9d71003282156n5ec025bbgd49283c14ea968b6@mail.gmail.com>
	<alpine.DEB.2.00.1003291210060.9798@aragorn.flymine.org>
	<bc7de5a31003290524k42878045ree4ef4f0333731e7@mail.gmail.com>

See http://www.postgresql.org/docs/current/static/storage-page-layout.html for
all of what is taking up the space.  Short version:
 Per block overhead is > 24 bytes
 Per row overhead is 23 bytes + some alignment loss + the null bitmap if you
have nullable columns

On Mon, Mar 29, 2010 at 8:24 AM, raghavendra t <raagavendra.rao@gmail.com>wrote:

> Hi Mattew,
>
> Thank you for the information.
>
> Once again, I like to thank each and everyone in this thread for there
> ultimate support.
>
> Regards
> Raghavendra
>
> On Mon, Mar 29, 2010 at 4:47 PM, Matthew Wakeling <matthew@flymine.org>wrote:
>
>> On Mon, 29 Mar 2010, Tadipathri Raghu wrote:
>>
>>> As per the documentation, one page is 8kb, when i create a table with int
>>> as
>>> one column its 4 bytes. If i insert 2000 rows, it should be in one page
>>> only
>>> as its 8kb, but its extending vastly as expected. Example shown below,
>>> taking the previous example table test with one column.
>>>
>>
>> There is more to a row than just the single int column. The space used by
>> a column will include a column start marker (data length), transaction ids,
>> hint bits, an oid, a description of the types of the columns, and finally
>> your data columns. That takes a bit more space.
>>
>> Matthew
>>
>> --
>> If you let your happiness depend upon how somebody else feels about you,
>> now you have to control how somebody else feels about you. -- Abraham
>> Hicks
>>
>> --
>> Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org
>> )
>> To make changes to your subscription:
>> http://www.postgresql.org/mailpref/pgsql-performance
>>
>
>

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