WooCommerce keeps track of user sessions and baskets in the woocommerce_sessions table, and if these can quickly fill up your database, particularly if you are subject to bots visiting your website.

The simple solution to this problem is to remove all sessions using the WooCommerce tool.  Note that this will end the sessions and empty all carts, including users who are currently on the site.

To expire all sessions,

• Navigate to WooCommerce > System Status
• Select the 'Tools' tab
• Click the "Clear all Sessions" button