The Architecture Tradeoff Analysis Method (ATAM) was developed by R. Kazman, M. Klein and P. Clements to evaluate early architectural decisions of software development in terms of quality attributes to avoid expensive architectural mistakes.  PostgreSQL developed in the University of California was a pioneer of many modern RDBMS systems. It is now an open source project.  We applied ATAM to the postgreSQL project in light of identifying the architectural features and possible pitfalls in the architecture of similar DBMS systems. The result shows that we identified some sensitive points, trade-off points and risks of postgreSQL although we did have some difficulties when extracting precise quality attributes. This work proves the effectiveness of ATAM method and explores the possible way to use ATAM on general purpose software.