Re: 8.2 is 30% better in pgbench than 8.3

Jim Nasby wrote:
> On Jul 22, 2007, at 8:54 AM, Josh Berkus wrote:
>> Tom,
>>> Note to all: we ***HAVE TO*** settle on some reasonable default
>>> vacuum_cost_delay settings before we can ship 8.3.  With no cost delay
>>> and two or three workers active, 8.3's autovac does indeed send
>>> performance into the tank.
>>
>> I've been using 20ms for most of my setups.  That's aimed at reducing
>> autovac to almost no impact at all, but taking a long time.  Maybe 10ms?
>
> I've found 20ms to be a pretty good number for run-of-the-mill IO
> capability, and 10ms to be good for a good RAID setup (RAID10, 8+ drives,
> BBU).
>
> For a default setting, I think it'd be better to lean towards 20ms.

OK, 20ms it is then.  Here is a patch.  I am taking the liberty to also
lower the vacuum and analyze threshold default values to 50, per
previous discussion.

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