vacuumdb --all Parallel Feature Request

Good afternoon folks.

I've been playing around with some vacuumdb options this week as part of
post-upgrade testing, in particular with parallel (--jobs=N). I noticed
that vacuumdb --all will only work on one database at a time. This means
that as it winds down to the last few tables in a particular database,
workers will be idle. For example, I ran with 8 jobs, but while 1 job runs
on the last big table of a particular database, the other 7 are doing
nothing.

It would be great if those idle jobs would be able to move on to the next
database to get a head start on the tables there. When you have big tables
in multiple databases in the cluster, it can make a big difference.

Also, running analyze_new_cluster.sh mentions this:

If you would like default statistics as quickly as possible, cancel
> this script and run:
> "/usr/pgsql-9.6/bin/vacuumdb" --all --analyze-only

I wonder if it wouldn't be a bad idea to also mention the --jobs=N
parameter option in that blurb. Yes it's in the --help text but it wouldn't
be bad to highlight its availability.

Don.

--
Don Seiler
www.seiler.us