Performance Enhancement of Read-only Transactions Using Speculative Locking Protocol T. Ragunathan and Dr. P. K. Reddy  Problems in Processing Read-only Transactions (ROTs) Correctness ( Serializability criteria) Data Currency ( Transactions receive old values) Performance ( Throughput)  The performance of 2PL degrades with data contention. Example:  Snapshot Isolation(SI)-based protocols violate serializability criteria and provide less data currency to ROTs. Example :  Proposed Speculation based approach (SLR) ROTs are processed with speculation. Whenever a UT produces after-image, ROTs access both before- and after-images and start speculative executions. ParametersValues # of objects in the database1000 Time to carry out CPU and I/O requests5ms and 10ms Size of the largest and smallest ROT20 and 15 objects Size of the largest and smallest UT15 and 5 objects  Simulation Parameters and Values.  Simulation Results  Throughput performance is Improved significantly over SI and 2PL.  Data currency of ROTs improved significantly over SI.  Requires manageable extra processing resources ( 1.4 times of memory is required).  Conclusions Proposed speculation based approach improves the performance of ROTs significantly over other protocols. It does not violate serializability criteria. It processes ROTs without data currency problems. The experimental results show that it requires manageable ( 1.4t imes) extra processing resources. Center for Data Engineering International Institute of Information Technology, Hyderabad Example:

Asynchronous Speculative Locking Protocol for improving the performance of Read-only Transactions - T. Ragunathan and Dr. P. K. Reddy  The performance of 2PL degrades with data contention.  Snapshot Isolation(SI)-based protocols violate serializability criteria and provide less data currency to ROTs.  Synchronous speculation based approach (SLR) Improves performance and data currency. ROTs wait for lock conversion ( EW-lock in to SPW-lock) ParametersValues # of objects in the database1000 Time to carry out CPU and I/O requests5ms and 10ms Size of the largest and smallest ROT20 and 15 objects Size of the largest and smallest UT15 and 5 objects  Requires manageable extra processing resources ( 1.5 times of memory is required).  Conclusions Proposed asynchronous speculation based approach improves the performance of ROTs significantly over other protocols. It does not violate serializability criteria. The experimental results show that it requires manageable ( 1.5 times) extra processing resources. Center for Data Engineering International Institute of Information Technology, Hyderabad Example:  Proposed Asynchronous speculative locking protocol (ASLR) ROTs do not wait for lock conversion and can start executions with the available before-images. However ROTs perform speculative executions whenever UTs produce after-images. When an ROT commits, it commits with the appropriate speculative execution. Performance is better than SLR.  Simulation Parameters and Values.  Simulation Results  Throughput performance is Improved significantly over SI, 2PL and SLR. Example: