Why do we still need a persistent layer?

The need for a persistent layer in a system such as SAP HANA primarily revolves around ensuring data integrity and security in the event of unforeseen circumstances, such as a power failure. This persistent storage acts as a safeguard, enabling full database recovery.

In typical database management systems, having a durable storage solution allows the system to retain essential data even when system memory is lost due to various failures. Without this layer, any changes made since the last save might be lost, compromising the consistency and reliability of the database. The persistent layer ensures that all committed transactions are securely stored and can be retrieved to restore the database to its last consistent state.

While some other options relate to specific functions of data management, such as handling new records or storing frequently used data, they do not address the critical aspect of recovery from system failures, which is a primary reason for having a persistent layer in place. Therefore, the focus on full database recovery highlights the essential role of persistent storage in maintaining reliable system operations.