F. Wu, J. K. Chen and Y. H. Chen
Institute of Computer Science
National Tsing Hua University
Hsinchu, Taiwan 300, R.O.C.
TBSAMlink, a variant of TBSAM, is an access methods for processing aggregate queries in a multi-user environment. Designs are made of deadlock-free operations which search and/or update a single data node or a range of data nodes. The correctness of these concurrent operations and the deadlock-free property are proved. When the techniques of right-link, lock-coupling, and the proposed rechecking are used to update the value in a single data node, at most two nodes are required to be locked. For updating a range of r (r>1) data nodes, at most r+1 nodes (r data nodes and one non-leaf node) should be locked. To evaluate the efficiency of these concurrent operations, mathematical formulas for the number of nodes to be accessed and/or locked are derived.
Keywords: aggregate query, concurrent operations, range updating, rang reading
Received Sepbember 27, 1993; revised February 23, 1994.
Communicated by Wei-Pang Yang.
*This work was supported by the National Science Coucil under Grant NSC82-0406-E007-243.