Re: Idea for getting rid of VACUUM FREEZE on cold pages

Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> writes:
> (As also discussed in the Royal Oak) I think we should simply not dirty 
> a page when a hint bit is updated. Reading a page from disk is 
> expensive, setting hint bits on the access is generally cheap compared 
> to that. But that is orthogonal to the idea of a per-page XID epoch.

I'm not sure it's cheap.  What you suggest would result in a substantial
increase in clog accesses, which means (1) more I/O and (2) more
contention.  Certainly it's worth experimenting with, but it's no
guaranteed win.
        regards, tom lane