Re: FSM, now without WAL-logging

On Mon, 2008-09-22 at 20:43 +0300, Heikki Linnakangas wrote:

> Attached is a revamped version of the FSM rewrite. WAL-logging is now 
> gone. Any inconsistencies between levels of the FSM is fixed during 
> vacuum, and by searchers when they run into a dead end because of a 
> discrepancy. Corruption within FSM pages is likewise fixed by vacuum and 
> searchers.
> 
> The FSM in a warm standby gets updated by replay of heap CLEAN WAL 
> records. That means that the FSM will reflect the situation after the 
> last vacuum, which is better than what we have now, but not quite 
> up-to-date. I'm worried that this might not be enough...

I hadn't realised you would remove it completely. Did you identify WAL
as the bottleneck?

Is there some mid-way point between every time and almost never
(VACUUM!)? 

-- Simon Riggs           www.2ndQuadrant.comPostgreSQL Training, Services and Support