Re: estimating table size - Mailing list pgsql-general

From Ian Barwick
Subject Re: estimating table size
Date
Msg-id 1d581afe04072615397222824f@mail.gmail.com
Whole thread Raw
In response to estimating table size  ("David Parker" <dparker@tazznetworks.com>)
Responses Re: estimating table size  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-general
On Mon, 26 Jul 2004 18:14:06 -0400, David Parker
<dparker@tazznetworks.com> wrote:
> Given a table, foo, created in a database but not populated, is there a
> procedure that will return an estimate of the size of a given tuple in
> that table? It looks like pgstattuple reports on actual table pages; I'm
> looking for something that reads the lengths of each row, and knows what
> the storage overhead would be (extra 4 bytes for varchar, for instance).
>
> Alternatively, is there documentation somewhere that can give me a good
> rule of thumb for this? I can add up the lengths of the columns and make
> my own judgements about averages for varchar columns. The "hidden"
> storage overhead is what I'm wondering about, I guess.

There is a little info in the FAQ:
http://www.postgresql.org/docs/faqs/FAQ.html

particularly sections 4.6 and 4.14

Ian Barwick
barwick@gmail.com

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