subject: Why would need to Join Extension Attribute to Entity? [print this page]
You need to join an extension attribute to an entity when your custom data is stored in a separate database table but must be fetched along with the main Magento entity, such as orders, customers, or products. For example, a Magento 2 order attributes extension often stores additional order-related details in a custom table. By joining the extension attribute, this data becomes available automatically when loading the order entity. This approach ensures cleaner architecture, improves performance, avoids manual SQL queries, and keeps the implementation fully compatible with Magento’s API and upgrade-safe design.
