Postgres as a Graph Database: (Ab)using pgRouting

pgRouting is a Postgres extension. It's often used for finding the “shortest path” between two locations, however it's a hidden gem in Postgres and can be used for basic graph functionality. pgRouting is typically combined with PostGIS for working with geospatial data, but it can also be useful beyond that as a lightweight alternative to Graph extensions like Apache AGE, or specialized graph datab