Sap Hana Savepoint Mechanism
Sap Hana is known as in memory database. So most of us have a curiosity that in case of any system crash or system restart event, what happen to our database. So in that case SAP Hana Savepoint is a functionality which keeps our database in persistent state.
All the changed pages are saved in the form of Savepoints, which are asynchronously written to persistent storage at regular intervals (by default, every five minutes). Savepoint are required to synchronize changes in memory persistent data on disk level. Redo logs are written to logs volumes(persistent storage) since the last Savepoint. The availability of recent Savepoint improves restart time of Sap Hana, because less redo logs need to be applied to make database consistent.
How Savepoint Works in SAP Hana:
When Savepoint are triggered:
Automatic: During normal operation savepoint are automatically triggered when a predefined time since last savepoint is passed.
The timeline of savepoint is configured by following parameter:
Global.ini > persistence > savepoint _interval_s
Manual: To execute a manual Savepoint use this command.
ALTER SYSTEM SAVEPOINT
Soft Shutdown: A soft shutdown invokes savepoint. Hard shutdown does not invoke savepoint.
Backup: A global Savepoint is invoked before a backup is started. A Savepoint is also performed after backup finishes.