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Background documentation Log Concept Locate the document in its SAP Library structure

One of the main internal functions of the SAP DB database system is logging.

In normal database operation (Structure linkoperational state ONLINE), the modifying SQL statements of every transaction must be logged, meaning that log entries (redo and undo log entries) are written. These log entries are required so that the database system can ensure transaction consistency and so that individual SQL statements can be reversed if required. In addition, the undo log entries are needed to enable consistent reading when no locks are set.

The task of online logging is to store the log entries so that they are constantly available for normal database operation.

In the case of a restart or restore, the required log entries must be made available and processed in the correct time-based sequence.

 

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