Concurrency control system for a relational DBMS using intent locks



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Concurrency control is essential to preserve the consistency of a shared database. The subject of this thesis is to implement Intent Lock Protocol using Two Pnase Locking concurrency control scheme to convert a single user relational DBMS (RRDS) to a multiuser (RRDS-M) system. The most commonly used concurrency control techniques are also discussed and compared. Intent Locking scheme allows simultaneous locking at various granularities by different transactions. Six modes of access to a shared object, NL, IS, IX , S, SIX, X are used. Intent Lock Protocol using Two Phase Locking not only balances concurrency and system overhead but also guarantees database integrity. This thesis also presents the way to create and install a shareable image under VAX/VMS. The use of shareable image for a multiuser DBMS system will conserve disk storage space, main physical memory and reduce paging I/O.



Database management, Electronic data processing--Distributed processing, Parallel processing (Electronic computers)