I read pgRouting as focusing on Geospacial routing to get from point A to point B. Is there more to it than that?

A graph database is about storing data that the relationships between pieces of data, like a social graph as an example. You'd have a people and the relationships between them in the database.

Despite the description on its website, at core, there's nothing particularly geospatial about pgRouting. You don't need PostGIS, or even Postgres's built-in geo types (point, line, etc.), in order to use pgRouting.

Rather, pgRouting is a set of general graph- and path-search algorithms, exposed as procedures, that operate upon rowsets (most efficiently, upon indexed tables) of vertices and edges. You can use pgRouting to do SPARQL-like graph queries, or even full-blown network analysis, if you like.

In a previous job, I did just that: I loaded up social-network data into vertex and edge tables, and then I used pgRouting's implementation of Floyd-Warshall and Driving Distance to discover high-value potential social connections within a given relationship-weighted distance of a given user. Not as a one-time data-science thing, but as the backend of our service's matching engine, that ran every time a user refreshed their "candidate matches" page. It was pretty instantaneous.

I remember wondering about exactly this a couple years ago, but I couldn't figure out the answer (I didn't look all that closely into it). Now I want to come up with an excuse to try it out on something. Thanks for mentioning this!

Wow, this is super neat. I wish I knew about this a couple years ago, it would've been super useful for a recommendation system I was building in production. I'll have to give this a shot!