Once the initial database migration has finished a new “Advanced” section will appear in the product settings tab (WooCommerce – Settings – Products – Advanced) with a couple of options related to this new feature:
“Use the product attributes lookup table for catalog filtering” instructs WooCommerce to effectively use the new lookup table for the shop catalog display and filtering, it will have been enabled automatically after the database migration finishes but you can enable and disable it at will (when disabled, the posts table will be used instead, as it was the case when the lookup table wasn’t available).
“Update the table directly upon product changes, instead of scheduling a deferred update” determines how the lookup table will be updated whenever a product is created or updated: when enabled, the update will happen immediately; otherwise, the action scheduler will do the update job some (short) time after the product is created or updated.
Important: WooCommerce will always create or update the appropriate entry in the lookup table whenever a product is created or updated, even when the “Enable table usage” setting is off. This is necessary to guarantee data consistency in all cases, regardless of whether the table usage is set on or off.