Historical data processing in real-time database system

RTDB(Real-Time DataBase) is the integration of traditional database technology and real-time system and is the core of SIS(Supervisory Information System). Historical data is the data regularly sampled from real-time database system and stored in historical database for user access. Historical database includes memory-based database and disk-based database. The former concerns the short-term data organization of sampled points while the latter manages the historical data files and management information files. The file structure and buffer area of disk-based historical database are described,and its general framework and implementation technology of some important function modules (read/write,compression,data page access) are elaborated in detail.