Re: freezing tuples ( was: Why is vacuum_freeze_min_age 100m? )

Josh Berkus <josh(at)agliodbs(dot)com> writes:
>> What are you envisioning exactly? If vacuum finds any reason to dirty
>> a page (or it's already dirty), then freeze everything on the page that's
>> got age > some lower threshold?

> I was envisioning, if the page is already dirty and in memory *for any
> reason*, the freeze rows at below some threshold.

I believe we've had this discussion before. I do *NOT* want freezing
operations pushed into any random page access, and in particular will
do my best to veto any attempt to put them into the bgwriter. Freezing
requires accessing the clog and emitting a WAL record, and neither is
appropriate for low-level code like bgwriter. The deadlock potential
alone is sufficient reason why not.

regards, tom lane