The following bug has been logged online:
Bug reference: 5200
Logged by: Andrew Masterton
Email address: a.j.masterton@open.ac.uk
PostgreSQL version: 8.3.8
Operating system: RedHat Enterprise 5.4
Description: Use of min suffix in autovacuum_naptime ignored
Details:
The default configuration of 8.3.8 has autovacuum_naptime = 1min. It would
appear that the min is ignored as turning up debug show the autovacuum
running every second. On my 8.3.8 installation with a large number of
databases and tables this has the side effect of the stats collector process
using up large amounts of CPU and I/O.
Changing this setting to 60min causes the autovacuum process to have the
correct 60 second naptime.
I Haven't tried removing the min and setting it to s to see if any time
suffix is ignored for this configuration option.