The Analysis And Research On Primary Technology Of Mobile Database

As the extension and expanding of the distributed database, mobile database, which has many excellences of distributed database and unique character itself, can satisfy the need that people want to get any information in any time wherever they are, therefore it has quite extensive foreground in application.In the mobile database system, because of the properties of the mobile environment such as mobility, frequent disconnection, network diversity, limited power .etc, the technique of the traditional distributed database can't sustain effectively the mobile environment; hence the research for the technique in the mobile environment is to be essential.Based on the domestic and international information, this paper mainly studies the replication technique and cache technique of the mobile database.and has done the work as follows:1) About the replication technique, based on the two-tier-replication, this paper introduces three-tier-replication and then proposes the periodical incremental maintenance algorithms with regard to the third tier replication (mobile client cache). Furthermore, it analyses the reason why three-tier-replication technique sustains effectively the mobile environment.2) About the cache technique, firstly this paper elaborates the reason why the traditional cache technique can't be effective in the mobile database and analyses the priority-based incremental update algorithm. Furthermore, one dynamic priority-based incremental update algorithms(DPIU) which considers two factors of data complexity and user's access probability is proposed The DPIU, which inherits the concept of data fresh and adds factors such as data complexity, makes up the shortages of the priority-based incremental update algorithm. Hence, the algorithm improves effectively the real-time and consistency in view update of mobile database, meanwhile caters to the demand of the mobile users.