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Function documentation Undo Log Management Locate the document in its SAP Library structure

Use

In ONLINE operational state, the database system writes undo log entries for all transactions that contain changing SQL statements. The database system can roll back the changes to a transaction that is not yet complete using undo log entries.

Rolling back transactions that are not yet complete is necessary with a ROLLBACK, for example, or if the database system is restarted after a power cut (see Using Log Entries With a Restart or Recovery).

Undo log management of the database system is primarily responsible for managing the undo log entries.

Activities

Undo log management saves the undo log entries to an undo log file in the data area.

Caution

In extreme cases, the data area may be full. In this case, expand the data area by adding volumes.

In general, the user task of the transaction deletes the corresponding undo log files at the end of the transaction. With liveCache database instances, the undo log files are not deleted after the end of a transaction, but are passed to the history management instead and are deleted by the garbage collector at a later time.

 

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