嵌入式移动实时数据库系统的恢复策略研究

华中科技大学硕士学位论文AbstractWith the rapid development of embedded technique and mobile technique,theperformance of embedded mobile devices has been greatly enhanced.Various applicationshave more and more requirements on real-timing.Embedded Mobile Real-time DatabaseSystem which integrates the mobile computation,real-time application and traditionaldatabase technology become a focus in the research of database,in which recoverytechnique is the key technique.The recovery system in this system should consider aboutthe limitation of resource,time and efficiency,so that the recovery could fit the demand ofreal-time and mobile characteristic.Besides maintaining the characteristics of traditional recovery,the mobile real-timerecovery should focus on how to store the log file in mobile hosts and base stations,strategy of handoff,and strategy of checkpointing.Algorithms for Recovery based on2-Level Log Using Ephemeral Log Dynamic Checkpoint Frequency(AR-2LL-ELDCF)is an effectual strategy of recovery in embedded mobile real-timedatabase.AR-2LL-ELDCF uses ephemeral log and only store in-use ephemeral log,which isuseful at ordinary recovery,in mobile hosts.The overdue ephemeral log is transferred tobase stations to store for the needs of audit.If the in-use ephemeral log is too large to storein the mobile host,it is sent to the base station.In this case it is needed to download thein-use ephemeral log to mobile host before recovery.AR-2LL-ELDCF uses dynamic checkpointing frequency to control the size of in-useephemeral log,so that it can be completely stored in the mobile host as far as possible.The strategy of handoff is closely cooperating with the stategy of in-use ephemeral logtransfer,which can reduce the recovery time.Keywords:Mobile real-time recovery,Ephemeral log,2-Level log,Handoff