ACID and BASE in PostgreSQL : DISTRIBUTED DATABASE PERFORMANCE

Abstract: This thesis studies the performance impact of the Two Phase Commit mechanism used in order to achieve consistency in a distributed PostgreSQL system. This impact is compared to the performance gained by removing Two Phase Commit and abandoning consistency. The tests are run on different number of nodes in the system to find a link between the performance hit and the size of the system. Performance is measured using the unit Queries per Second. Firstly, a short introduction is given to demonstrate why and when distributed database systems is necessary and the difficulties it poses. Thereafter follows a description of the system constructed to conduct the experiment, together with the results of this experiment. The thesis is concluded with a discussion regarding the results and thoughts on future variations of the experiment. The conclusion of the experiment is that Two Phase Commit puts a low maximum performance on the system, especially when compared to the alternative of abandoning consistency. The number of nodes did not significantly affect the performance of the system using Two Phase Commit, however the alternative had a clear negative correlation between numbers of nodes and Queries per Second.