mobilitydb-duckdb-bridge

Generated DuckDB loadable extension that bridges the mobilitydb DataFission wasm shim into DuckDB as native scalar functions, aggregates, UDTFs, custom column types, and identity casts.

Produced by ducklink-shim-codegen from a shim-interface SQLite database. Do not edit by hand — regenerate from the source.

The upstream mobilitydb-wasm shim covers 100% of the wireable temporal surface — all six subsystem scaffolds (temporal, tjsonb-agg-ops, tile UDFs, structural merge/append, windowed aggregates, span union) are landed along with the recent correctness cascade closing 51 silent-bug fixes.

Surface

Extension	Version	Scalars	Aggregates	UDTFs	Windows	Types	Operators	Casts	Preprocessors	Catalog	Indexes
mobilitydb	0.1.0	2130	63	43	0	116	32	36	1	0	0

Build

cargo build --release

The build needs sibling checkouts of the path-dep'd workspace crates (datafission-df-plugin-loader, datafission-df-plugin-api, datafission-functions) at ../datafission/crates/.

Package as a loadable extension

DuckDB only loads files ending in .duckdb_extension that carry a metadata footer matching the target DuckDB version. The extension-template-rs project ships a helper script for this:

python3 path/to/append_extension_metadata.py \
  -l target/release/libmobilitydb_duckdb_bridge.dylib \
  -n mobilitydb_duckdb_bridge \
  -p osx_arm64 \
  -dv v1.2.0 \
  -ev v0.1.0 \
  -o mobilitydb_duckdb_bridge.duckdb_extension \
  --abi-type C_STRUCT

Adjust -p to your platform (linux_amd64, linux_arm64, osx_amd64, …). Pin -dv to the DuckDB version you target.

Load + use

The bridge needs the composed shim wasm at runtime; set MOBILITYDB_SHIM_WASM before LOAD:

-- Need DuckDB CLI with -unsigned since we don't sign the bridge.
MOBILITYDB_SHIM_WASM=/path/to/mobilitydb-composed.wasm duckdb -unsigned
> LOAD '/path/to/mobilitydb_duckdb_bridge.duckdb_extension';

Regen

When the upstream shim's SQL surface changes:

cd ~/git/ducklink-shim-codegen
cargo run --release -- \
  --interface /path/to/mobilitydb-interface.sqlite \
  --out ~/git/mobilitydb-duckdb-bridge

The codegen pipes every emitted .rs through rustfmt --edition 2021, so the resulting crate is cargo fmt -p mobilitydb-duckdb-bridge -- --check-clean by construction.

Architecture

• Scalars: dispatched through duckdb-rs's VScalar trait (vectorised; one chunk per invoke).
• Aggregates + custom types + identity casts: raw libduckdb-sys FFI — duckdb-rs doesn't surface these in its safe wrapper.
• Entrypoint: hand-rolled extern "C" symbol named mobilitydb_duckdb_bridge_init_c_api (NOT the #[duckdb_entrypoint_c_api] macro) so we can pull both a raw duckdb_connection AND a Connection wrapper.
• Custom types like GEOMETRY / STBOX register as BLOB aliases; identity casts in both directions let CREATE TABLE t (g GEOMETRY); INSERT INTO t VALUES (st_geomfromtext(...)) round-trip.

License

Apache-2.0. Generated source so the same license as the codegen.