Processing time-constrained aggregate queries in CASE-DB
ACM Transactions on Database Systems (TODS)
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THIS PAPER PRESENTS RESULTS OF EMPIRICAL EVALUATIONS CARRIED OUT ON THE RT-CARAT TESTBED. THIS TESTBED WAS USED FOR EVALUATING A SET OF INTEGRATED PROTOCOLS THAT SUPPORT REAL-TIME TRANSACTIONS. USING A BASIC LOCKING SCHEME FOR CONCURRENCY CONTROL, SEVERAL ALGORITHMS FOR HANDLING CPU SCHED- ULING, DATA CONFLICT RESOLUTION, DEADLOCK RESOLUTION, TRANSACTION WAKEUP, AND TRANSACTION RESTART ARE DEVELOPED AND EVALUATED. THE PERFORMANCE DATA INDICATES (1) THAT THE CPU SCHEDULING ALGORITHM HAS THE MOST SIGNIFICANT IMPACT ON THE PERFORMANCE OF REAL-TIME TRANSACTIONS, (2) THAT VARIOUS CONFLICT RESOLUTION PROTOCOLS WHICH DIRECTLY ADDRESS DEADLINES AND CRITICALNESS PRODUCE BETTER PERFORMANCE THAN PROTOCOLS THAT IGNORE SUCH INFORMATION, (3) THAT DEADLOCK RESOLUTION AND TRANSACTION RESTART POLICIES TAILORED TO REAL-TIME CONSTRAINTS SEEM TO HAVE NEGLIGIBLE IMPACT ON OVERALL PERFORMANCE, (4) THAT CRITICALNESS OF TRANSACTIONS IS A VERY IMPORTANT FACTOR IN REAL-TIME TRANSACTION PROCESSING, AND (5) THAT DEADLINE DISTRI- BUTIONS STRONGLY AFFECT TRANSACTION PERFORMANCE. WE BELIEVE THAT THESE RESULTS REPRESENT THE FIRST EXPERIMENTAL RESULTS FOR REAL-TIME TRANSACTIONS FROM AN ACTUAL SYSTEM.