To get rid of heavy archive logs in PostgreSQL 9.1
If you don't need to analyze again that log. You can reduce the things that database will be log.
Some of them are:


log_statement: Controls which SQL statements are logged. You don't need to log all statement. It can be switched to none.
client_min_messages: can be set to ERROR
log_min_messages: can be set to ERROR
log_min_duration_statement: can be set to a -1 - this means disable it.


All of them are store in file configuration postgresql.conf

You can read more document here.

Hopefully this answer will help you.