Re: Bufer cache replacement LRU algorithm?

Mladen Gogala wrote:
> Where can I find the documentation describing the buffer replacement
> policy? Are there any parameters governing the page replacement policy?

I wrote a pretty detailed description of this in my "Inside the
PostgreSQL Buffer Cache" presentation at
http://projects.2ndquadrant.com/talks and nothing in this specific area
has changed significantly since then. There aren't any specific
tunables in this area beyond the ones that cover sizing of the buffer
pool and how often checkpoints happen. There's a TODO item to benchmark
toward whether there's any gain to increasing the maximum usage count an
individual page can accumulate, currently hard coded at 5. That's the
main thing that could be tunable in this area that currently isn't.

--
Greg Smith 2ndQuadrant US greg(at)2ndQuadrant(dot)com Baltimore, MD
PostgreSQL Training, Services and Support www.2ndQuadrant.us
"PostgreSQL 9.0 High Performance": http://www.2ndQuadrant.com/books