Concurrency Control of Large Unstructured Data

Current research projects and database product extensions re ect the importance of unconventional database applications (for example, document processing and computer aided design). Unconventional applications di er from the conventional ones (for example, airline reservation) in the nature of transactions and data. The transactions may be complex, long and involve human interaction. The data includes small, structured objects as well as large, unstructured objects. The unstructured objects are stored in and managed by unstructured data base management systems (UDS). A UDS employs coarse-granularity locking which limit the concurrency and reduce the throughput of transactions. This paper deals with this problem of coarsegranularity locking at a UDS. It proposes and investigates the logical concurrency control (LCC) concept as a solution. In LCC, a software module sits on top of the UDS and o ers a higher-level service. This module employs application-domain-speci c negranularity locking to achieve high concurrency.