i have the same problem; 60000 row-data is logged per minute, it's okay while inserting but when data is requested for reporting, it takes too long.
a friend of mine advised me using distributed databases: there should be master and summary databases. the master db holds the latest data and the others store older data. the data stored in master database should be moved to other databases in a period of time/limited size. by doing it, the size of the db can be smaller and the searching can be easier.