The project provides the framework for implementing different optimizer algorithms and allows a user to switch between different implementations or to implement his own optimizer.
The Pluggable Optimizer Interfaceproject is a PostgreSQL Community project that is a part of the pgFoundry.
The pgFoundry page for the project is at http://pgfoundry.org/projects/optimizer, where you can find downloads, documentation, bug reports, mailing lists, and a whole lot more.
