Re: Unexpected page allocation behavior on insert-only tables

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: Michael Renner <michael.renner@amd.co.at>
Cc: pgsql-hackers@postgresql.org
Date: 2010-05-16T00:16:47Z
Lists: pgsql-hackers
Michael Renner <michael.renner@amd.co.at> writes:
> I've written a simple tool to generate traffic on a database [1], which 
> did about 30 TX/inserts per second to a table. Upon inspecting the data 
> in the table, I noticed the expected grouping of tuples which came from 
> a single backend to matching pages [2]. The strange part was that the 
> pages weren't completely filled but the backends seemed to jump 
> arbitrarily from one page to the next [3]. For the table in question 
> this resulted in about 10% wasted space.

Which table would that be?  The trigger-driven updates to "auction",
in particular, would certainly guarantee some amount of "wasted" space.

			regards, tom lane