Abstract
Real-time database systems are designed to handle workloads where transactions have completion deadlines and the goal is to meet these deadlines. However, many real-time database environments are characterized by workloads that are a mix of real-time and standard (non-real-time) transactions. Unfortunately, the system policies used to meet the performance goals of real-time transactions often work poorly for standard transactions. In particular, optimistic concurrency control algorithms are recommended for real-time transactions, whereas locking-based protocols are suited for standard transactions. In this paper, we present a new database system architecture in which real-time transactions use optimistic concurrency control and, simultaneously, standard transactions use locking. We prove that our architecture maintains data integrity and show, through a simulation study, that it provides significantly improved performance for the standard transactions without diminishing the real-time transaction performance. We also show, more generally, that the proposed architecture correctly supports the co-existence of any group of concurrency control algorithms that adhere to a standard interface.
Highlights
A real-time database system (RTDBS) is a transaction processing system that is designed to handle workloads where transactions have completion deadlines
We present a new database architecture that allows different transaction classes to choose from multiple concurrency control schemes and execute simultaneously without loss of data integrity
We have addressed the issue of designing integrated real-time database systems that can cater to transaction workloads which have a mix of firm-deadline real-time transactions and standard transactions
Summary
A real-time database system (RTDBS) is a transaction processing system that is designed to handle workloads where transactions have completion deadlines. We present a new database architecture that allows different transaction classes to choose from multiple concurrency control schemes and execute simultaneously without loss of data integrity. Apart from maintaining consistency, the integration scheme provides improved performance for the standard transactions and does this at no cost to the RTDBS’s primary concern: real-time performance This was confirmed by a detailed simulation study of the MCC architecture implemented in a RTDBS whose input workload has both real-time transactions and standard transactions. [2,3,5, 311) and RTDBS users may wish to take advantage of these new algorithms Note that this “open” feature of our architecture makes the integration scheme applicable in not just the real-time database context but in any environment where there are multiple transaction classes with different preferred CC algorithms. We have designed algorithms to implement recovery for our RTDBS architecture - the details are omitted here due to space limitations but are described in [41]
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