Re: Expose checkpoint start/finish times into SQL.

Theo Schlossnagle <jesus@omniti.com> writes:
> Heikki: It it useful for knowing when the last checkpoint occurred.

I guess I'm wondering why that's important.  In the current bgwriter
design, the system spends half its time checkpointing (or in general
checkpoint_completion_target % of the time).  So this seems fairly close
to wanting to know when the bgwriter last wrote a dirty buffer --- yeah,
I can imagine scenarios for wanting to know that, but they probably
require a whole pile of other knowledge as well.

JD seems to have gone off into the weeds imagining that this patch would
provide tracking of the last N checkpoints; which might start to
approach the level of an interesting feature, except that it's still not
clear *why* those numbers are interesting, given the bgwriter's
propensity to try to hold the checkpoint duration constant.

            regards, tom lane