Incorporating load factor into the scheduling of soft real-time transactions for main memory databases

Many real-time applications have very tight time constraints which couldn´t be met by disk resident databases. For those applications, main memory databases where entire databases are stored in main memory are the proper choice. It has been shown that coarse-granule locking is better than fine-granule locking for main-memory databases. Coarse-granule locking makes it easy to extract data access patterns correctly from canned transactions of main memory real-time database systems. In this paper, we propose two real-time transaction scheduling algorithms-CCA-ALF (Cost Conscious Approach with Average Load Factor) and EDF-CR-ALF (Earliest Deadline First-Conditional Restart with ALF)-which use both static (e.g., deadline) and dynamic information (e.g., system load) for main memory databases by utilizing data access patterns of transactions. We compare the performance of those algorithms with CCA and EDF-HP which do not use system load information. Our simulations on main memory databases indicate that: i) CCA-ALF is better than EDF-HP, CCA, and EDF-CR-ALF in terms of miss percent and mean lateness, and ii) CCA-ALF adapts well to the changes in the system load