Distributed Database Housekeeping Rules

Christopher. J. Date is known for his prominent work with relational database theory  and for formulating  the 12  basic principles of distributed databases. Date like Edgar. F. Codd was involved with IBM and wrote extensively about relational databases .

It appears, inspired by his colleague's "Codd’s 12 commandments" of relational database management system (RDBMS), Date formulated twelve basic principles of distributed databases. Although no current Distributed Database Management System conforms to all of them, they serve as a reference line for optimized allocation of databases and to keep the extent of  double duplicity of databases in check.

C. J. Date's Twelve Commandments For Distributed Databases 

1.     Local site independence. Each local site can act as an independent, autonomous, 

       centralized DBMS. Each site is responsible for security, concurrency control,  

       backup, and recovery.  

2.    Central site independence, No site in the network relies on a central site or any  

       other site. 

3.     Failure independence The system is not affected by node failures. The system 

        is in continuous operation even in the case of a node failure or an expansion of   

        the network. 

4.     Location transparency. The user does not need to know the location of data in 

        order to retrieve those data. 

5.     Fragmentation transparency. Data fragmentation is transparent to the user, 

        who sees only one logical database. The user does not need to know the name of  

        the database fragments in order to retrieve them. 

6.     Replication transparency .The user sees only one logical database. The  

        DDBMS transparently selects the database fragment to access. To the user, the 

        DDBMS manages all fragments transparently. 

7.     Distributed query processing. A distributed query may be executed at several  

        different DP sites. Query optimization is performed transparently by the  

        DDBMS. 

8.     Distributed transaction processing. A transaction may update data at several  

        different sites, and the transaction is executed transparently. 

9.     Hardware independence. The system must run on any hardware platform. 

10.   operating system independence. The system must run on any operating system  

        platform. 

11.   Network independence. The system must run on any network platform. 

12.   Database independence. The system must support any vendor's database  

        product.

(C. J. Date's twelve commandments for distributed databases)

These requirements are not limited to RDBMS's but extent to  the multi-media friendly ODBMS as well.  The rules have become a measure for evaluating distributed databases and they enable the database modeller to make better modelling decisions. (C. J. Date Rules)


Reference

"C. J. Date Rules." Scribd. N.p., n.d. Web. 6 Aug. 2012.
    <http://www.scribd.com/doc/26882380/C-J-Date-Rules>.
"C. J. Date's twelve commandments for distributed databases ." C. J. Date's twelve
    commandments for distributed databases . N.p., n.d. Web. 6 Aug. 2012.
    <www.uobabylon.edu.iq/uobColeges/ad