Structuring the Commit Tree for Better Performance of Two Phase Commit Processing

Extensive research has been carried out in search for an efficient atomic commit protocol and many optimizations have been suggested to improve the two-phase commit protocol, either for the normal or failure case. Yet, the performance effects on transaction processing when combining some of these optimizations have not been studied in depth. In this paper, we concentrate on the flattening-of-the-commit-tree optimization, in particular the combination of flattening with the read-only optimization. Our simulation results reveal a major pitfall of flattening when dealing with large trees. A new restructuring method is proposed that performs better than flattening even when dealing with large trees. Required protocol modifications to support the suggested optimizations are also addressed.