Research On Mobile Database Synchronization Model Based On Self-organizing Domain And Relational Transaction Result Set

With the improvement of mobile network speed and the performance of mobile terminal equipment,mobile computing plays a more and more important role in people's work and life,and the synchronization of mobile database is becoming more and more important.Because of its frequent disconnection,mobility and asymmetric network conditions,mobile computing environment makes it more complex with the data synchronization between servers in the traditional fixed network.At present,the common mobile synchronization architecture is: two level replication,three level replication and so on.In three level replication,the interaction of synchronous server and mobile terminal uses centralized structure,and the direct interaction between mobile terminal and synchronous server will increase the load of the synchronization server,and the synchronization service can be considered as the hardware performance of the mobile terminal is greatly improved and the communication technology between mobile terminals is mature.Part of the pressure of the device is shared by the mobile terminal.Therefore,this paper adopts a hybrid mobile database synchronization architecture based on centralized architecture and ad hoc architecture.The difficulties in the synchronization of mobile database are: the influence of frequent disconnection of the mobile network,the limited bandwidth of the mobile terminal,and the inconsistency of data brought by the data distribution storage.These problems restrict the stability,reliability and performance of mobile computing system.Therefore,this paper makes further optimization and innovation on the basis of the existing mobile database synchronization scheme,in order to better improve the synchronization efficiency and data consistency of the mobile database.This paper optimizes the synchronous data upload volume and transaction rollback rate in mobile environment.The specific optimization work is as follows: on the basis of the mobile computing architecture,on the basis of the original three level duplication structure,the centralized architecture and the ad hoc architecture are used mixed;at the synchronization granularity,the transaction level synchronization is adopted,and the scheme is based on the related transaction,which is directly connected with the result set and passed through.In the SOD self organization domain,the non service mobile terminal only accepts the operation of the read-only transaction,and makes it direct access to the service mobile terminal for non read-only transactions.In this way,on the service mobile terminal,the transaction result set is connected to the update transaction within the entire SOD,and it has a certain synchronization optimization effect.In the optimization of synchronous downloading data,the data sheet is divided into public table,shared table and private table,which corresponds to different synchronization processing.In the acquisition of incremental data,the time stamp + trigger + synchronization user reservation table is adopted to reduce the communication pressure of the uplink band and the synchronization server is used.The data broadcast capability periodically sends invalid data and time limit data to the mobile database,detects the failure data and time limit data on the service mobile terminal,further reduces the possibility of transaction rollback,reduces the communication pressure of the uplink bandwidth,and carries out conflict transactions on the service mobile terminal.Rollback can roll back possible conflict transactions more,reduce the rate of transaction rollback at the synchronous server level;identify various pseudo update conflicts,such as the formula: write value + current read value-write value dependent reading values;for insert conflicts,because they are mainly caused by the same primary key,so on some tables,such as user notes.The primary key can be added to avoid collisions;using the associated transaction merge unit,you can discard a transaction before a transaction,and other transactions are rolled back,which can be rolled back according to the sequence of interrelated transactions and what associations are associated;internal SOD within the organization domain.The data is highly consistent,and the synchronization of a service terminal is equivalent to all terminal synchronization within the SOD,and the newly added SOD members may carry the latest version of the data.In the case of not being connected to the synchronous server,the synchronization can be organized by itself,and the possibility of transaction rollback is reduced further.