Study On Lock Of DBMS

As an important branch of computer softwares, Database Management System is a complex one. DBMS is a powerful tool to manaf e mass data very efficiently. Database Management System is used to provide duration storage, programming interfaces and the ability to manage transaction.In order to support the ACID of concurrency transactions, high concurrency and high performance, DBMS must maintain the serializabiiity of transactions by using a kind of concurrency control.The dispatcher is in charge of it.There are there technics for dispatcher-lock based, timestamp based and validation based.OSCAR uses the dispatcher based on lock.This dissertation focuses on the design and implementation of OSCAR'S lock management module. Two-phase Locking Protocol and Tree Locking Protocol can be implemented on this system.This module implements multiple granularity lock(three levels), automatic lock and automatic lock escalation.And it supports deadlock detection.