Serial protocol for transaction execution in main-memory database systems

Abstract

A method for improving the performance of a system having a main-memory database which has at least one database containing at least one data item, and having a permanent storage device. The system executes at least one update transaction for modifying the data item to produce update results, and at least one read transaction for reading the data item. The method includes the steps of requiring the update transaction to acquire a database mutex before the update transaction modifies the data item. A timestamp is assigned to the update transaction and to the data item to be updated by the update transaction. After the update transactions updates the data item and before it release the database mutex, the update transaction acquire a mutex associated with the timestamp. Before the update's results are stored to the permanent storage device, the update transaction releases the database mutex. Finally, the update transaction releases the mutex associated with the timestamp after the update's results are stored to the permanent storage device. Before a read transaction is allowed to read the data item, the read transaction must acquire the database mutex. To ensure that the read transaction read data that was committed by the predecessor update transaction, the read transaction must acquire and release the mutex associated with the timestamp before the read transaction terminates.