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 Undo Log File 

Undo log files contain the undo log entries that are created by the user tasks for modifying SQL statements. Each undo log entry in an undo log file is given an undo log sequence number, starting with 0.

Undo log files are stored in the data area.

In exceptional circumstances, storing the undo log files in the data area can cause the data area to become full. If this happens, you need to increase the size of the data area.

Undo log files are deleted as follows:

·        MySQL MaxDB: At the end of a transaction, the undo log files are deleted by the user task of the transaction.

·        SAP liveCache: At the end of a transaction, the undo log files are transferred to history management, because they are needed to enable data to be read consistently without any locks being applied. They are deleted later by the garbage collector.

 

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