Magento creates lots of files and database entries no one really needs. So here is how I tried to clean up the mess – based on this script from the magento site http://www.magentocommerce.com/wiki/groups/227/maintenance_script
First I logged in into the shell and executed the following in the magento directory:
rm -rf var/cache/* var/log/* var/report/* var/session/* var/tmp/* media/import/*
After that I executed the following SQL queries:
truncate table dataflow_batch_export; truncate table dataflow_batch_import; truncate table log_customer; truncate table log_quote; truncate table log_summary; truncate table log_summary_type; truncate table log_url; truncate table log_url_info; truncate table log_visitor; truncate table log_visitor_info; truncate table log_visitor_online; truncate table report_event;