Magento 2 EE design give more importance to how magento can scale without much effort. As a part this, magento 2 database can be split into 3 master databases.
- One master database for checkout tables
- One master database for order management system (OMS) tables
- One master database for the remainder of the Magento 2 application tables
Checkout, orders, and product data can all each use a separate master databases that you can optionally replicate. This separation independently scales load from website checkouts, order management activities, website browsing, and merchandising activities, depending on your needs. These changes provide considerable flexibility in how the database tier can be scaled.Splitting of database also helps in managing the databases like backup, restoring etc, for a single large databases these tasks are tedious.
For scaling further more you can add slave databases for each master DB and so you can scale to any limit in server clusters using load balancers. This feature is not available in Magento 2 community edition 🙁