Hybrid-TH: a hybrid access mechanism for real-time memory-resident database systems

The objective of this paper is to develop a high performance access mechanism for real-time memory-resident database systems. Real-time systems have very important properties: timeliness and predictability. In conventional database systems, hashing is known faster than tree access mechanism on the simple searches. Hence, on some environments, hash can be more appropriate to the real-time applications. On the other hand, tree index mechanism, it is possible to search to a range of specific data. Depending on the distance of a node in the tree, however, each access time to a node in the tree is different. This feature is not desirable for real-time database application, which requires deterministic data access behavior. In this paper, we present a new combined access mechanism called Hybrid Tree-Hash (Hybrid-TH) mechanism. This mechanism is a complementary integration of tree-index and hash-index structure assuring that a Worst-Case Execution Time is bounded within a specific time, especially, when range search operation works. Our analysis shows that Hybrid-TH provides the predictability of data access operation in real-time memory-resident database systems (DBMS).