Sdml Storage-based Concurrency Control

Along with the development of internet application, XML became the standard of the data description and data commutative. As the huge numbers of XML document flushed into the internet, the problem of effective XML data storage and querying became emergent. Now a common method to this problem was putting XML data to the RDBMS (Relation Database Manager System), using SQL selection method to fetch XML data. This method can make use of the developed RDBMS products and resolve part of the XML data's storage and query problem based on the well developed RDBMS theories.Although the research and application of the RDBMS theories were well developed, there were many problems in the storage of XML using the RDBMS mechanism. Those problems contained follows. The traditional XML data structure was a tree and the storage structure of the RDBMS was a table with two dimension. When the XML data structure changed into the RDBMS data structure, the semantics messages could be lost. The query of the XML data such as XPath and XQuery could not execute on the RDBMS, it must be switched to the query of SQL mode. Using the SQL query mode, the query result should change back to the tree mode of XML data, which leading the low efficiency.For those problems, this laboratory designed and developed a storage platform-SDML independently. It stored the XML data with the Native mode, which kept down the tree structure of the XML data and support the query of XPath and XQuery. This paper researched integrated theories and implement of inter-current control based on the lock mechanism on the foundation of SDML storage platform. Those theories could resolve the access bottleneck owing to the big blank granularity in the inter-current mode.At now, the lock granularity of the XML database was the whole XML document and the inter-current arrangement of the afire was on the document layer. With the growing of the application document, this granularity may become a bottleneck of the whole system. Because of the above reason, this paper has been...