In this paper, we construct a simulation model for OODBS and carry out several performance evaluation studies on these two Class-Hierarchy Locking protocols and the Non Class-Hierarchy Locking (NCL) protocol. Th
Lock based protocol: This protocol requires that all the data items must be accessed in a mutually exclusive manner, i.e. when one transaction is executing then no other transaction should interrupt the same object. To implement lock based protocol we need 2 types of locks. Shared Lock:When ...
In a locking protocol, each time a transaction requests access to a data item, it must also tell the DBMS the type of access it requires. If a transaction requests shared access to an item that is either unlocked or locked with a shared lock, that access is granted and the item is mar...
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Deadlock may be especially likely if the instant transaction waits on this lock since the normal protocol is to lock in order of coarse to fine granularity (table, block, then row), whereas in this case an upgraded block lock is being sought after the row lock is already in place. The ...
4) Locking protocol 加锁协议 1. The tree locking protocol,introduced by Silberschatz and Kedem,was defined based on static tree-structured data. 随着XML数据库管理系统 (XMLDBMS)研究的日益深入 ,研究基于树型结构的XML数据的并发控制协议变得十分重要 由Silberschatz和Kedem提出的树加锁协议 (treeprotocol...
XML/ XPath-based locking protocolXML databaseconcurrency controlquery language/ C6160 Database management systems (DBMS) C6130D Document processing techniquesProviding efficient access to XML documents becomes crucial in XML database systems. More and more concurrency control protocols for XML database ...
Summary: Based on XTC, we have redesigned, reimplemented, and reoptimized BrackitDB, a native XML DBMS (XDBMS). Inspired by "optimal" concurrency gained on XTC using the taDOM protocol, we applied an XML benchmark on BrackitDB running now on a substantially different computer platform. We ...
There are thus not many choices for a victim. Hence, it may not be wise to use a sophisticated but expensive deadlock breaking protocol. Most commercially available database systems use lock-based c...
In client-server database management systems (DBMSs), inter-transaction caching is an effective technique for improving the performance. However, inter-transaction caching requires a cache consistency maintenance (CCM) protocol to ensure that chached copies at clients are kept mutually consistant. Such...