Research On The Transaction And The Concurrency Control Mechanism Of NXD Database

A variety of information platform based on network play an important role in different areas, access and exchange of information resources need the way of database, along with the development of the network, XML shows great vitality, a large number of documents were compiled with XML, and so, being XML database that restore and manage the XML-formatted data put an unprecedented challenge on traditional databases field.As one of the most basic concepts in the development of databases, transaction has been widely used in variety of the E-commerce and the enterprise information platform. Certainly, XML database must have a sound mechanism for transaction processing that is an extremely important to concurrent access for multi-user. The suitable way of design to the concurrency mechanism is transference from the XML document to the relational database according to the rules generally, thus, the concurrency transactions of XML data can be guarantied by the relatively perfect concurrency mechanisms of relational database. However, the fact was found in practical applications, that is the way above-mentioned cannot take efficiency on the concurrency control of XML document truly, because of the great difference exist in the graphic data of XML document and planarity of data of the traditional database, and we didn't highlight it in details earlier. Studies on concurrency control mechanisms of the native XML database has just begun, this paper aims at the solution of this question and go further more exploration actively.This paper use the experience of multi-versioning for reference, offer a transaction management model of XML databases based on the XPath and a controlling mechanism of the mufti-users concurrency transaction. First of all , to define a sort of database node code based on document tree model which make the operation of update enable, next, the set of XML database operation is defined according to the encoded data model. eventually, this paper propose a concurrency control mechanisms and lock model, and the lifting method for transaction when dead-lock occurred, also verify the serial scheduling of transaction schedule based on lock protocol, this concurrency control mechanisms can be applied to the management of multi-transaction.