PostGraph provides a bridge between PostgeSQL and the Boost Graph Library. We aim to support a number of graph theory options useful in spatial connectivity analysis. The current version implements custom graph classes that wrap SQL edge tables. These classes are compatible with the graph concepts defined in the BGL and can be reused with many algorithms. The graph classes contain no data, only prepared query plans that are executed on-demand when algorithms request access to vertex and edge lists permitting analysis of extremely large graphs. Our recent testing shows that some algorithms scale well to 50,000,000 edges (and perhaps beyond -- we simply stopped there).