The visitor log is a feature that can help you see what traffic is coming in to your site right now and identify visitors you want to keep away.
On active sites with a lot of visitors the size of the database table can grow big very quickly. You can reduce how long the visitor logs are kept to keep down the size.
To change this go to your WordPress admin, find the “Security Ninja” menu item and go to the “Firewall” tab.
Scroll down to the settings and find “Visitor Logging”. Here you can change the dropdown value “Keep visitor logs for”.
You can change the interval between 1, 3, 7, 14 and 30 days. Per default the visitor log files are kept for 7 days.
Security Ninja runs an automated job twice daily to remove old log entries from the database.
You can also turn on/off the visitor log to completely disable this feature.