ACID and BASE in POSTGRESQL : Distributed database performance

Abstract: This thesis studies the performance impact of the Two Phase Commitmechanism used in order to achieve consistency in a distributed Post-greSQL system. This impact is compared to the performance gainedby removing Two Phase Commit and abandoning consistency. Thetests are run on different number of nodes in the system to find a linkbetween the performance hit and the size of the system. Performanceis measured using the unit Queries per Second.Firstly, a short introduction is given to demonstrate why and whendistributed database systems is necessary and the difficulties it poses.Thereafter follows a description of the system constructed to conductthe experiment, together with the results of this experiment. The the-sis is concluded with a discussion regarding the results and thoughtson future variations of the experiment.The conclusion of the experiment is that Two Phase Commit putsa low maximum performance on the system, especially when com-pared to the alternative of abandoning consistency. The number ofnodes did not significantly affect the performance of the system us-ing Two Phase Commit, however the alternative had a clear negativecorrelation between numbers of nodes and Queries per Second.