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Background documentation New Developments in SAP DB Version 7.4 Locate the document in its SAP Library structure

I/O Management

·        No system volume
There is no longer a system volume.
The converter pages are all distributed across all data volumes.

·        No converter cache
The converter pages and data pages are kept in a shared I/O buffer cache.
You now only require the database parameter CACHE_SIZE for the configuration of the size of the I/O buffer cache.

·        Parallel converter queries (multi-region converter)
The converter can now be accessed in multiple critical regions at the same time.

·        It is possible to read from and write to the converter simultaneously.

Database Size Can Be Reduced

·        The size of the database is independent of the largest page number used for a data page. In some circumstances, gaps in the sequence of the page numbers can mean that the database is significantly smaller than suggested by the highest number.

Log Management

Note

See also log concept in Background Knowledge: SAP DB and log settings.

·        Abolition of the log cache
Log entries are created directly in the log wait queue.

·        Before and after images split
Before images are stored in transaction-specific undo log files in the data area.
After images are stored in the log area.

·        Parallel writing of before images
For transactions, the before images are saved in transaction-specific undo log files, independent of other transactions.

·        The overwrite mode setting is no longer connected to the log mode.

·        You can temporarily deactivate the redo log management.

Data backups

·        Checkpoints are obsolete.

·        Each data backup is consistent internally. This means that you can start the database instance after importing the data backup without needing to import log entries. The state of the data then matches the state when the data backup was started. You can use the log entries in the log area or in log backups to restore the state of the database instance to a chosen time after the data backup.

·        Incremental data backups contain all changes since the last complete data backup
This simplifies the restore process. When you restore the database instance, you need only to import the last complete data backup and the last incremental data backup, as well as the log entries required for your chosen point-in-time.

 

 

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