Cannot get log_min_duration_statement to work

Question

I have been googling for more than 2 hours, but I am really stuck with this one.
I want PostgreSQL (I am using version 8.4 on Debian) to start logging slow queries only.

To that extend I use the following configuration in postgresql.conf:

log_destination = 'csvlog'
logging_collector = on
log_min_messages = log
log_min_duration_statement = 1000
log_duration = on
log_line_prefix = '%t '
log_statement = 'all' 

The rest of the configuration is all on default settings (commented out). The logging works, but it logs all statements, even the ones below the threshold of 1000 (ms). If I do a 'show all' I see that all settings are in effect. I also tried restarting Postgres.

I hope someone can help me out.

Answer 1

log_statement = 'all'

instructs the server to log all statements, simple as that. In addition:

log_duration = on

also instructs the server to log all statements, including duration info.
Change that to:

log_statement = none
log_duration = off

No quotes needed. Or comment them out and reload. Then no statement will logged, except those running longer than 1000 ms - instructed by:

log_min_duration_statement = 1000

It's all in the excellent manual.