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Re: Optimizer showing wrong rows in plan

From: Matthew Wakeling <matthew(at)flymine(dot)org>
To: Tadipathri Raghu <traghu(dot)dba(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Jeremy Harris <jgh(at)wizmail(dot)org>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Optimizer showing wrong rows in plan
Date: 2010-03-29 11:17:50
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
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.


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