Re: Clock sweep not caching enough B-Tree leaf pages?

* Merlin Moncure (mmoncure(at)gmail(dot)com) wrote:
> I don't think this would work unless we would keep some kind of
> tracking information on the page itself which seems not worth a write
> operation to do (maybe if the page is dirtied it could be snuck in
> there though...). IOW, it would only make sense to do this if we knew
> that this page was likely to be read in again. This might be true in
> general on particular workloads but is probably a pretty flimsy
> assumption without supporting evidence; probably better to let the O/S
> deal with it.

The trouble is that we're ending up "hiding" the information from the OS
about the frequency of utilization of that page. You have a good point
and we wouldn't want to do this for pages that are just accessed once or
similar, but perhaps just mark a page that's reached the 'max' as having
been 'hot' and then, for those pages, advise the OS that while we're
under pressure and need to push this page out, it was once pretty hottly
used and therefore we may want it again soon.

For pages that never reach the 'max' level, we wouldn't do anything on
the assumption that those were only temporairly needed.

Just some thoughts.

Thanks,

Stephen