Re: Rethinking stats communication mechanisms

"Magnus Hagander" <mha@sollentuna.net> writes:
> Might it not be a win to also store "per backend global values" in the
> shared memory segment? Things like "time of last command", "number of
> transactions executed in this backend", "backend start time" and other
> values that are fixed-size?

I'm including backend start time, command start time, etc under the
heading of "current status" which'll be in the shared memory.  However,
I don't believe in trying to count events (like transaction commits)
that way.  If we do then we risk losing events whenever a backend quits
and is replaced by another.

I haven't yet looked through the stats in detail, but this approach
basically presumes that we are only going to count events per-table and
per-database --- I am thinking that the background stats collector
process won't even keep track of individual backends anymore.  (So,
we'll fix the old problem of loss of backend-exit messages resulting
in bogus displays.)
        regards, tom lane