Lock-based concurrency control for XML
Ahmed, Namiruddin · eScholarship@McGill (McGill) · 2006
As XML gains popularity as the standard data representation model, there is a need to store, retrieve and update XML data efficiently. McXml is a native XML database system that has been developed at McGill University and represents XML data as trees. McXML supports both read-only queries and six different kinds of update operations. To support concurrent access to documents in the McXML database, we propose a concurrency control protocol called LockX which applies locking to the nodes in the XML tree. LockX maximizes concurrency by considering the semantics of McXML's read and write operations in its design. We evaluate the performance of LockX as we vary factors such as the structure of the XML document and the proportion of read operations in transactions. We also evaluate LockX's performance on the XMark benchmark [16] after extending it with suitable update operations [13]. Finally, we compare LockX's performance with two snapshot-based concurrency control protocols (SnaX, OptiX) that provide a committed snapshot of the data for client operations.