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Re: estimating table size

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Ian Barwick <barwick(at)gmail(dot)com>,David Parker <dparker(at)tazznetworks(dot)com>, pgsql-general(at)postgresql(dot)org
Subject: Re: estimating table size
Date: 2004-07-27 03:28:08
Message-ID: 200407270328.i6R3S8k11181@candle.pha.pa.us (view raw or flat)
Thread:
Lists: pgsql-general
I just updated the FAQ to suggest 32 as the header size (I am assuming
OID's and 4-byte alignment).  I am also assuming 7.5 which will loose
the cmin/cmax compression.

---------------------------------------------------------------------------

Tom Lane wrote:
> Ian Barwick <barwick(at)gmail(dot)com> writes:
> > There is a little info in the FAQ:
> > http://www.postgresql.org/docs/faqs/FAQ.html
> > particularly sections 4.6 and 4.14
> 
> I think the calculation in section 4.6 is out of date --- it's been
> awhile since row headers were 36 bytes.  The more correct number is
> between 24 and 32 bytes depending on whether you created the table
> WITH OIDS and whether your machine requires 4- or 8-byte alignment.
> 
> 			regards, tom lane
> 

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