When restarting the SAP HANA database system, it follows a specific sequence to ensure data integrity and system stability. The correct sequence is represented by option C:
* Row tables are loaded into memory:Initially, the row-based tables are loaded into memory.
Row-based storage is typically used for tables that are not frequently involved in aggregation queries or do not benefit significantly from compression. Loading these tables first allows for immediate access to critical transactional data.
* Open transactions are recovered:Next, the system recovers any transactions that were open at the time of the previous shutdown. This step is crucial for ensuring data consistency and completeness, as it allows the database to complete or revert transactions that were in progress, maintaining the ACID (Atomicity, Consistency, Isolation, Durability) properties of the database.
* Aborted transactions are rolled back:Following the recovery of open transactions, the system then rolls back any transactions that were aborted and did not complete successfully. This step is necessary to ensure that the database does not retain any partial or corrupted data from failed transactions.
* Column tables are loaded:Finally, column-based tables are loaded into memory. Columnar storage is optimized for read-heavy operations and is typically used for analytical queries that benefit from high data compression and fast aggregation. Loading these tables last allows the system to prioritize immediate transactional processing needs while progressively enabling full analytical capabilities.
This sequence ensures a balanced and efficient restart of the SAP HANA database, prioritizing immediate transactional data availability while methodically restoring the full analytical processing environment.