Python wheel should export DuckDB C API symbols (or provide a path to them)

[nelson2005]

What happens?

Prior to 1.4.1, the DuckDB Python wheel exported all C API symbols on every platform. Starting with 1.4.1, duckdb-python#81 restricted exports to only PyInit__duckdb and duckdb_adbc_init via linker flags in CMakeLists.txt L83-L110.

On macOS, -exported_symbol is a hard allowlist — all C API symbols are gone. On Linux, --export-dynamic-symbol is additive, so all symbols remain visible as a side effect. This means the C API works on Linux today but is broken on macOS — and could break on Linux too if a version script is added in the future.

Version	macOS C API symbols	Linux C API symbols
1.3.x	~6,300 ✅	~6,300 ✅
1.4.0	~6,300 ✅	~5,900 ✅
1.4.1+	0 ❌	~5,900 ✅ (by accident)
1.5.x	0 ❌	~6,300 ✅ (by accident)

This is a breaking change for projects that load the C API from the Python wheel.

Use case

numbduck wraps 160 DuckDB C API functions for use inside numba @njit compiled code. It loads the shared library from the installed duckdb Python package and resolves C API symbols at runtime. This worked on all platforms through duckdb 1.4.0, but breaks on macOS starting with 1.4.1.

The standalone libduckdb downloads have all symbols, but requiring a separate install (brew install duckdb) alongside pip install duckdb is a friction point — users expect the Python package to be self-contained.

Possible solutions

1. Export all duckdb_* C API symbols from the Python wheel on all platforms. The symbols are already compiled into the binary — they're just hidden by the linker flags.
2. Add a ctypes-friendly entry point — e.g. a function that returns a pointer to a struct of C API function pointers (similar to how duckdb_adbc_init works for ADBC).
3. Bundle libduckdb.dylib/.so alongside the Python extension in the wheel, so ctypes.CDLL can load it directly.
4. Document the limitation — if the C API is intentionally not part of the Python wheel's public interface, document that C API consumers should use the standalone libduckdb downloads.

Option 1 is the smallest change — just remove the linker flags. The PR #81 commit message says these are "the only two [symbols] that are ever needed," but that assumes all consumers go through Python or ADBC.

Environment

• duckdb 1.4.1 through 1.5.1 (macOS broken; Linux works by accident)
• macOS ARM64 and x86_64
• Verified with nm -gD / nm -g on installed wheel .so files