GeoDesk has the advantage of being more compact than other database formats for OSM data (only a bit bigger than OSM PBF) with fast creation and query times. Currently, GeoDesk databases can’t be updated, but it appears the GeoDesk team is working on supporting updates.
I’m not sure how this compares to other approaches for building tiles on demand (e.g. using PostGIS) or if it’s a viable alternative for some use cases. My use case is to rapidly iterate on the still-evolving schema I’m using for Ascend Maps at GitHub - styluslabs/maps: 3D maps for iOS, Android, and desktop
The tile schema is defined by a C++ function called for each feature intersecting the tile, similar to the Lua script used by tilemaker. Currently, only the schema for Ascend Maps (which tries to use unmodified OSM tags as much as possible) is implemented but implementing other schemas such as OpenMapTiles would be straightforward and I’d be happy to do this if there was interest.
So far I’ve tested this with a regional extract, but plan to set up a global server soon (if anyone has suggestions for hosting options cheaper than AWS, let me know).