Keys have nothing to do with database locking. Locking is a mechanism to support serialisation.
Reading and writing is possible with or without locking. Locking is a mechanism to support serialisation.
Locking is a mechanism to support serialisation. Without locks, all simultaneous transactions can occur in ways which prevents serialisation. Two-Phase locking enforced serialisation, while still allowing trasactions which do not interfere with each other to occur simultaneously. All simultaneous transactions are not prevented unless they all interfere with each other.
Locking is a mechanism to support serialisation. If two-phase locking is used, serialisation can be enforced. If transactions are serialisable, then the results are consistent...
- Keys can be provided to maintain security.
- Reading and writing is possible.
- All simultaneous transactions are prevented.
- Passwords can be provided to maintain security
- Consistency can be enforced.
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