Research On Technologies Of RDBMS's Buffer Adaptive Management

The problem of the expansion of database functionality and scale, and the growing complexity of database tuning has become more and more severe in practice. Adaptive database is a rising technology which shifts the responsibility of database tuning from the DBA onto the DBMS itself to reduce the manage cost and improve the performance of database system. Management technology in buffer is one of the key technologies of DBMS. Adaptive management technology in buffer related to DBMS will be put forward based on researches of relevant issues.To implement adaptive management technology in buffer related to DBMS, a cost evaluation model on the basis of an accessing mode is constructed through analysis of features of load so that read ahead algorithm, replace policy and mergence of I/O in DBMS buffer can be adaptively adjusted. The parameter of this model is clearly indicates features of load to a certain degree. Also it can be directly and quickly obtained form the DBMS to reduce unnecessary cost.With regard to traditional replace policy in buffer, the thesis propounds an improved adaptive LRU replace policy on basis of researches on merits and faults of various algorithms. Grounded on a cost evaluation model based on an accessing mode, the arithmetic adopts the improved adaptive replace policy to relieve the work load required for LRU replace policy and hence strengthens the accuracy in buffer.Basically DBMS buffer aims at a reduction of the frequency of DBMS I/O. If the work load features in a sequence accessing data, DBMS buffer will further merge sequential-addressed I/O automatically and decrease I/O frequency to improve the performance of the database system.The thesis conducts analysis on features of adaptive systems and applies adaptive feedback system in manage module of the DBMS buffer with reference to the system structure of DBMS. The purpose is to minimize changes of the system structure of the original system as well as negative effects and to clarify its structure and better its expansion.DM is a China-making DBMS with an independent copyright. Adaptive management technology in buffer adopted in DM means to apply adaptive algorithm and adaptive feedback system in buffer to DM database management system. Researches show it is practical that adaptive management technology in buffer enables DM database to automatically adjust management in buffer and improve system performance under different work loads.