Reload in a main memory database system: MARS

The authors introduce two different algorithms to perform a complete reload of data from secondary storage (AM) into main memory (MM) when a system crash occurs: ordered reload with prioritization and smart reload. The first algorithm uses a cylinder as its reload granularity and does not take the access frequency into consideration. The second algorithm uses a block as its reload granularity and makes use of access frequency. Both algorithms allow the system to be brought online before the entire database is reloaded and implement the same priority reload scheme: the highest priority is given to data needed by executing transactions, the second highest priority to data needed by waiting transactions, and the last priority to the remaining data. Reload of data of lower priority is preempted by reload of data of higher priority to achieve faster system response time