When moving a large Magento Database or simply cleaning a Magento Database, it is safe to Empty but not Drop the following tables:
dataflow_batch_export
dataflow_batch_import
log_customer
log_quote
log_summary
log_summary_type
log_url
log_url_info
log_visitor
log_visitor_info
log_visitor_online
report_viewed_product_index
report_compared_product_index
report_event
