Title
 Speculation based nested locking protocol to increase the concurrency of nested transactions

P.Krishna Reddy, and M.Kitsuregawa   
 Institutue of Industrial Science, University of Tokyo, Japan

Reference
 P.Krishna Reddy and Masaru Kitsuregawa, Speculation based nested locking protocol to increase 
 the concurrency of nested transactions, International Database Engineering and Applications 
 Symposium (IDEAS2000), September 18-20, 2000, Yokohoma, Japan, IEEE Computer Society Press.  
 
Abstract
 The authors propose an improved concurrency control protocol based on speculation for nested 
 transactions and explain how it increases both intra and inter-transaction concurrency as compared 
 to J.E.B. Moss's (1985) nested locking protocol. In the proposed speculative nested locking 
 (SNL) protocol, whenever a sub-transaction finishes work with a data object (produces after-image), 
 it's parent inherits the lock. The waiting sub-transaction carries out speculative executions by 
 accessing both before- and after-images of preceding sub-transaction and selects appropriate 
 execution after the termination of the preceding subtransaction. In this way, SNL allows multiple 
 executions to be carried out for a transaction by trading extra processing and main memory 
 resources to increase concurrency.