Know that a client server database system provides simultaneous access to the database for multiple clients.
Know how concurrent access can be controlled to preserve the integrity of the database.
Concurrent access can result in the problem of updates being lost if two clients edit a record at the same time. This problem can be managed by the use of:
- record locks
- serialisation
- timestamp ordering
- commitment ordering
Information about which records are currently being accessed will be maintained. When a user tries to access a record, check this information and only permit access if the record is not currently being used.
Database changes are grouped as transactions and queued. Database software processes the queue (FIFO).