Main Memory Database Technology Research And The Construction Of A Prototype System

Main memory DBMS is a branch of DBMS technologies. It decreases the response time, increases the throughput,and adapts to many real-time systems by loading the entire database into memory, simplifying the operations and condensing the code. A prototype of MMDB is introduced in this thesis on the basis of research and discussion. Database structure definition, object store structure definition, log record type and structure definition, OID management are realized in this prototype. This paper is focused on the log-based recovery and T tree technologies. In the process of checkpoint, WAL(Write-Ahead Logging) rule does not permit updating the database before the corresponding log records having been written into the log file. WAL not only has serious effects on the performance of the database system but also makes coding complex. The Ping-Pang checkpoint algorithm to be realized in this thesis is not confined by the WAL, and it can make the system more efficiently and decrease the system response time remarkably.T tree, which is the most significant index structure in MMDB, is used not only as index but also as database free spaces manager in this prototype.Moreover, atomic operation, hybrid logging, database spaces pseudo-release policy, group commit, two-way-scan recovery and synchronous database loading algorithm are adopted in this prototype. Simple performance tests and analyses are given in the end of this thesis.