Re: Unexpected page allocation behavior on insert-only tables

On 16.05.2010 02:16, Tom Lane wrote:
> 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.

Yeah, the auction table receives heavy updates and gets vacuumed regularly.

The behavior I showed was for the "bid" table, which only gets inserts 
(and triggers the updates for the auction table).

best regards,
Michael