New Developments in SAP DB Version
7.4 
New I/O Management
·
No system
volume
The system volume no longer exists.
The converter pages are distributed among 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 regions at the same time.
Database 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.
· The number of data volumes at the time of the database restart can be different from the number of data volumes at the time of the backup.
New Log Management
·
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 save
of before images
In parallel transactions, the before images are saved in parallel in
transaction-specific undo log files.
New Data Backup
· 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 recover 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 recovery process. When you recover 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.