Before Release Magento 2.3 we are using in custom module development, Tables created by InstallSchema & upgraded by UpgradeSchema, similarly InstallData to install data in tables & UpgradeData to upgrade data in tables, this process was time-consuming Once Release Magento 2.3 [ 25th Nov, 2018 ], introduced new concept of Database Creation is declarative schema … Continue reading What is Declarative Schema in Magento 2.x