How to configure rsyslog to log into PostgreSQL without too much latency?
Solution 1:
Did you read http://www.rsyslog.com/doc/rsyslog_high_database_rate.html before applying the configuration from there? The article says that the configuration there does exactly what happens in your case: The output is buffered in memory and on disk before writing it to the database.
If you don't want the output to get buffered, you should just use the configuration from http://www.rsyslog.com/doc/rsyslog_pgsql.html without applying the other stuff.