Index Technologies For The Embedded Active Real-Time Database ARTs-EDB

Real-time database (RTDB) needs to face the challenge of simultaneously satisfying data integrity and timing requirements. The transactions and data in real-time database systems have explicit time constraints, and the correctness of transaction execution relies on not only the logical results but also the time constraint. In general, RTDB requires the support of main-memory database system. Index is an efficient tool that can improve the DBS'executing performance. Establishing index in MMDB must be influenced by quick access and efficient use of the memory.ARTs-EDB is an embedded active real-time database system, which is researched and developed independently and possesses proprietary intellectual property rights. It is based on the support of main-memory database system. A large number of data reserves in the main-memory, leading to the result that the time spending on searching the aiming data in the main-memory can not be ignored. Therefore, in the MMDB, except for the use of traditional index, another index that supports to search data in the main-memory should be introduced. And the non-primary index is used more frequently and designed more complicatedly than the primary index.After analyzing the characteristics of the non-primary index used to search the data in the main memory, a new non-primary index system is designed and implemented which fits to MMDB. The index is implemented as a inverted table index that supports range and united search, and the united search is implemented with a quick algorithm rather than a united index. The experiment demonstrates that the new index structure has better performance of searching and needs less main memory than the hashing table. The defect of the index structure is that it needs a more complicated establishing algorithm. Therefore, the system introduces popularity diagnose sub-system to support the new index structure.Popularity diagnose sub-system classifies the attribute by the use frequency during a latest period of time at the present and some other elements. The system determines whether it needs establishing and reserving the non-primary index by the classification of the attribute. Reserving the popular index with limited main memory supports high index shooting average, on the premise that the system needn't establish non-primary index frequently.The experiments'result based on ATRs-EDB shows that the above index strategy can greatly improve the time and spatial performance than the traditional index strategy.