Geobuf Index

[mourner]

Lets discuss indexing. Previous discussion: #27 (comment)

I think the solution I'd like to see here is a separate PBF-based format that would come as a separate file coupled with a Geobuf file that would store:

• serialized R-Tree (rbush) with leafs pointing to feature offsets in the geobuf pbf
• a map of feature ids to feature offsets for fast single-feature seeking

The R-tree serialization should avoid embedded messages because they are hard to decode lazily. I'd imagine one possible solution to be nodes stored as a flat set of messages, with references to children implemented as offset pointers.

[district10]

I implemented this idea. proto: https://github.com/cubao/geobuf-cpp/blob/dev/geobuf_index.proto

test: https://github.com/cubao/geobuf-cpp/blob/b06e682bae6f04ad9147659edbd8eecb9dfe2d3f/tests/test_geobuf.py#L1918