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This graphic is explained in the accompanying text Example: Restart Locate the document in its SAP Library structure

A restart has to be performed because of a system failure. The database system restores the database instance starting from the time of the last savepoint.

The following figure shows how the database system handles the transactions for a restart.

Status of the transactions at the time of a system failure

This graphic is explained in the accompanying text

Handling the transactions during a restart

Transaction

Required Action

T1

None

The changes to transaction T1 were saved completely by the last savepoint before the failure.

T2, T3

None

The changes made before the savepoint have to be rolled back. The redo tasks evaluate the corresponding undo log files.

T5

None

The changes from T5 were rolled back before the system breakdown and have not yet been saved in the data area.

T4, T6

The log reader creates the redo log files and corresponding entries in the redo list. The redo tasks import the necessary redo log entries.

 

 

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