Enabling autovacuum by default (was Re: Autovacuum improvements)

Tom Lane wrote:

> Actually the reason it's not enabled by default today has nothing to do
> with either of those; it's
> 
> 3. Unexpected side effects on foreground processes, such as surprising
> failures of DROP DATABASE commands.  (See archives for details.)
> 
> Until (3) is addressed I don't think there is any chance of having
> autovac on by default, and so worrying about (1) and (2) seems a bit
> premature.  Or at least, if you want to work on those fine, but don't
> expect that it will alter the fact that the factory default is "off".

With that taken care of, do I dare propose enabling autovacuum by
default, so that further changes will be picked up quickly by the
buildfarm?

Attached is a patch to do so, based on Peter's last attempt at doing
this.

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.