More logging for autovacuum

I'm having trouble following what's going on with autovacuum and I'm finding
the existing logging insufficient. In particular that it's only logging vacuum
runs *after* the vacuum finishes makes it hard to see what vacuums are running
at any given time. Also, I want to see what is making autovacuum decide to
forgo vacuuming a table and the log with that information is at DEBUG2.

So I would like to suggest adding two options:

log_autovacuum_jobs - output every time a vacuum or analyze *starts*

log_autovacuum_level - set the log level for the autovacuum process

I would also suggest raising the level of the DEBUG2 message indicating why
tables were chosen or not. At least to DEBUG1 if not to INFO.

Am I missing anything? Are there ways to get this info already that I'm
missing? I imagine it would be pretty simple to add these and I'll be happy to
do it and send the patch to -patches assuming others (Alvaro? :) agree.

--  Gregory Stark EnterpriseDB          http://www.enterprisedb.com