Database Reference
In-Depth Information
Rule 8: Distributed Transaction Management
Each transaction must be atomic — fully committed or fully rolled back. This objective
must be met irrespective of the agents (constituent processes) of the transaction.
Concurrency control must be ensured (usually by data locking).
Rule 9: Hardware Independence
It should be possible to integrate the system across different hardware platforms.
It should therefore be possible to run the DBMS on different hardware systems.
Rule 10: Operating System Independence
It should be possible to integrate the system across different operating system platforms.
It should therefore be possible to run the DBMS on different operating systems.
Rule 11: Network Independence
The system should be able to support different sites with different hardware and different
operating systems and networking protocols.
Rule 12: DBMS Independence
The DBMS suites used may be different. For instance DB2 and Oracle both support SQL
and open database connectivity (ODBC); it should therefore be possible to link databases
running on the two DBMS suites. The same argument should apply for other DBMS suites.
22.4 Challenges to Distributed Database Systems
Distributed databases did not come easily; neither were they easy to maintain.
Fortunately, the software engineering industry has figured out how to address these
challenges. However, improving the algorithms used, and finding new ones are always
topical research issues. There are five well known challenges to distributed database
systems. These are:
•
Query Optimization
•
Catalog Management
•
Update Propagation
•
Concurrency Control
•
Transaction Management
