On 01/23/2012 11:16 PM, Robert Treat wrote:
I keep thinking Greg has mistaken happiness with the MB based info in the vacuum patch as being happy without the output format, when really it is all about increased visibility.
I haven't taken that as anything but evidence I'm at least moving in the right direction. I'm relatively systematic about how I approach these things nowadays: figure out what isn't being logged/accounted for yet, add visibility to that thing, iterate on improving its behavior as measured by that, then make the best sorts of behavior changes automatic. This suggested feature change, moving around what I see as the worst part of the tuning knob UI, is an initial attempt along step 3 in that path. There's still plenty of ongoing work adding more visibility too.
To more quickly summarize the point I was trying to make, providing a meter that trivially shows you good vs. bad is the almost same problem as making it fully automatic. If you can measure exactly when something needs to happen and how badly screwed up it is, that's the hard part of knowing when to just go fix it. Right now, the autovacuum measure is based on the percent of change to something. I don't think any improved vacuum triggering will go somewhere useful unless it starts with a better measure of how real-world bloat accumulates, which you cannot extract from the data collected yet. The free space measurement thread and the ideas that have mainly been bouncing between Jaime and Noah recently on this subject are directly addressing that, the part that I've found to be the single most useful additional thing to monitor. It may not be obvious that's providing information that can be consumed by autovacuum, but that was my intention for how these pieces will ultimately fit together.
-- Greg Smith 2ndQuadrant US g...@2ndquadrant.com Baltimore, MD PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
