Re: Displaying accumulated autovacuum cost

On 08/18/2011 10:54 AM, Peter Eisentraut wrote:
> So how about adding a column to pg_stat_activity, progress_metrics or
> something like that, and add that information there.
>

Adding a field here (I'd go for the simpler "progress") and updating it
regularly would be a reasonable way to go here. This data doesn't
really need to go into the traditional statistics infrastructure to be
useful. I didn't start there because I was already getting pushback on
overloading the stats collector with constantly updated metrics last
time I did something in this area. I wasn't going to try and argue why
it was worth it in this case, just like I'm not going to argue about the
complaint over the command string overhead being too high--just going to
not do that instead. If the bikeshed I built doesn't look fancy enough
to hold the bike I put in there, I'm not going to build a better one
right now--I'll just put a cheaper bike in there instead.

I was hoping to eventually take the useful summary bits at the end, the
totals, and save those into statistics somewhere each time a VACUUM of
either sort finishes. It would fit with the information shown in
pg_stat_tables, but that's obviously getting too wide. Breaking out a
pg_stat_autovacuum view that contains all the relevant bits currently
shown in that view, plus these 3 new fields, would be a reasonable start.

--
Greg Smith 2ndQuadrant US greg(at)2ndQuadrant(dot)com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.us