How do I install the DuckDB-Extensions skill?

Run npx skillmds@latest add lawless-m/duckdb-extensions in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

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Is DuckDB-Extensions free to use?

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Who published DuckDB-Extensions?

lawless-m (@lawless-m) published this skill. Their other Agent Skills are listed on their SkillMD profile.

DuckDB-Extensions by lawless-m — Agent Skill

Name: DuckDB-Extensions
Rating: 4.2 (5 reviews)
Author: lawless-m

File contents

DuckDB Extensions

Building .duckdb_extension files with CMake + FetchContent. The gotchas below all cost real debugging time.

Critical gotchas

Exact version match: the extension MUST be built against the exact DuckDB version that will load it. Use FetchContent with a specific git tag (e.g. v1.2.1), never main. Version strings need the v prefix (v1.2.1, not 1.2.1) or loading fails with a version mismatch.
Metadata append is REQUIRED: DuckDB rejects extensions without appended metadata ("The file is not a DuckDB extension. The metadata at the end of the file is invalid"). Add a POST_BUILD command running ${duckdb_SOURCE_DIR}/scripts/append_metadata.cmake, and add_dependencies(${TARGET_NAME} duckdb_platform) — the duckdb_platform target generates the duckdb_platform_out file the metadata step reads.
Const bind_data (DuckDB 1.1+): bind_data is const during execution ("increment of member in read-only object"). Put mutable state in a GlobalTableFunctionState subclass, register an init_global, and access it via input.global_state.
Platform ABI mismatch: "built for platform 'linux_amd64', but we can only load extensions built for platform 'linux_amd64_gcc4'" means the system DuckDB has a different ABI. Easiest fix: use the DuckDB binary from your own build at build/release/_deps/duckdb-build/duckdb.
PIC: any static library linked into the shared extension needs POSITION_INDEPENDENT_CODE ON.

Deployment

Auto-discovery install path: ~/.duckdb/extensions/v{version}/{platform}/ (e.g. ~/.duckdb/extensions/v1.2.1/linux_amd64/myextension.duckdb_extension).
In ~/.duckdbrc, LOAD must come BEFORE any SET of extension-registered settings — the settings don't exist until the extension loads.
Unsigned (dev) extensions need duckdb -unsigned. Use a wrapper script so it's never forgotten:

#!/bin/bash
# ~/.local/bin/duckdb (ahead of the real duckdb in PATH)
exec /path/to/actual/duckdb -unsigned "$@"

References

Full CMakeLists template (static linking, metadata POST_BUILD, PIC/relocation troubleshooting): reference-cmake.md
Entry-point and table-function C++ boilerplate, custom settings registration: reference-cpp-patterns.md

---name: duckdb-extensionsdescription: Use when building, debugging, or deploying a DuckDB loadable extension — version matching, "not a DuckDB extension" errors, install paths, auto-loading.---# DuckDB ExtensionsBuilding `.duckdb_extension` files with CMake + FetchContent. The gotchas below all cost real debugging time.## Critical gotchas1. **Exact version match**: the extension MUST be built against the exact DuckDB version that will load it. Use FetchContent with a specific git tag (e.g. `v1.2.1`), never `main`. Version strings need the `v` prefix (`v1.2.1`, not `1.2.1`) or loading fails with a version mismatch.2. **Metadata append is REQUIRED**: DuckDB rejects extensions without appended metadata ("The file is not a DuckDB extension. The metadata at the end of the file is invalid"). Add a POST_BUILD command running `${duckdb_SOURCE_DIR}/scripts/append_metadata.cmake`, and `add_dependencies(${TARGET_NAME} duckdb_platform)` — the `duckdb_platform` target generates the `duckdb_platform_out` file the metadata step reads.3. **Const bind_data (DuckDB 1.1+)**: `bind_data` is const during execution ("increment of member in read-only object"). Put mutable state in a `GlobalTableFunctionState` subclass, register an `init_global`, and access it via `input.global_state`.4. **Platform ABI mismatch**: "built for platform 'linux_amd64', but we can only load extensions built for platform 'linux_amd64_gcc4'" means the system DuckDB has a different ABI. Easiest fix: use the DuckDB binary from your own build at `build/release/_deps/duckdb-build/duckdb`.5. **PIC**: any static library linked into the shared extension needs `POSITION_INDEPENDENT_CODE ON`.## Deployment- Auto-discovery install path: `~/.duckdb/extensions/v{version}/{platform}/` (e.g. `~/.duckdb/extensions/v1.2.1/linux_amd64/myextension.duckdb_extension`).- In `~/.duckdbrc`, `LOAD` must come BEFORE any `SET` of extension-registered settings — the settings don't exist until the extension loads.- Unsigned (dev) extensions need `duckdb -unsigned`. Use a wrapper script so it's never forgotten:```bash#!/bin/bash# ~/.local/bin/duckdb (ahead of the real duckdb in PATH)exec /path/to/actual/duckdb -unsigned "$@"```## References- Full CMakeLists template (static linking, metadata POST_BUILD, PIC/relocation troubleshooting): `reference-cmake.md`- Entry-point and table-function C++ boilerplate, custom settings registration: `reference-cpp-patterns.md`

Frequently asked questions

DuckDB-Extensions