[maxxen]

Thanks! I've been wanting to add this since I first started out working on DuckDB almost two years ago but I finally managed to accumulate the time (and the skills required!) to finish it up over the summer. It still has a long way to go, support for indexes in extensions are pretty... raw, and we only push down constant filters into index scans (so no spatial index-join acceleration yet). But I think having a proper spatial index is one of those things that are kind of required to really elevate the spatial extension from being just a toy and I'm super stoked to work more on it during the next release cycle and all the new possibilities that it opens up.

[maxxen]

I still need to update the docs and there's probably going to be a blog post on it in the future, but for now there are some more details in the PR https://github.com/duckdb/duckdb_spatial/pull/383