Implementation:Duckdb Duckdb Add Third Party

Metadata

Field	Value
Type	Implementation (API Doc)
Source Files	`CMakeLists.txt:L778-780` (function definition), `CMakeLists.txt:L802-813` (invocations)
Domains	Build_System

Overview

Concrete tool for compiling vendored third-party libraries into static libraries provided by DuckDB's CMake build system. The add_third_party() CMake function is a thin wrapper around add_subdirectory() that standardises the source and binary directory paths for every vendored dependency. Each invocation brings a third-party library's CMakeLists.txt into the build graph, compiling it into a static archive that is subsequently linked into DuckDB's core targets.

Code Reference

Function Definition

function(add_third_party NAME)
    add_subdirectory(
        ${_DUCKDB_PROJECT_SRC_DIR}/third_party/${NAME}
        ${_DUCKDB_PROJECT_BIN_DIR}/third_party/${NAME}
    )
endfunction()

Parameters:

Parameter	Type	Description
`NAME`	String	Name of the third-party library directory under `third_party/`

The function resolves two paths:

Source directory: ${_DUCKDB_PROJECT_SRC_DIR}/third_party/${NAME} -- the vendored source tree containing the library's own CMakeLists.txt.
Binary directory: ${_DUCKDB_PROJECT_BIN_DIR}/third_party/${NAME} -- the out-of-source build output directory for that library.

Invocations

The following vendored libraries are compiled via add_third_party():

add_third_party(fastpforlib)
add_third_party(fmt)
add_third_party(fsst)
add_third_party(hyperloglog)
add_third_party(libpg_query)
add_third_party(mbedtls)
add_third_party(miniz)
add_third_party(re2)
add_third_party(skiplist)
add_third_party(utf8proc)
add_third_party(yyjson)
add_third_party(zstd)

I/O Contract

Inputs

Input	Location	Description
Third-party source trees	`third_party/<NAME>/`	Vendored source code for each dependency
Per-library CMakeLists.txt	`third_party/<NAME>/CMakeLists.txt`	Build declaration for each vendored library (defines the static library target, source files, compile flags)
`_DUCKDB_PROJECT_SRC_DIR`	CMake variable	Root of the DuckDB source tree
`_DUCKDB_PROJECT_BIN_DIR`	CMake variable	Root of the DuckDB build output tree

Outputs

Each invocation produces a static library target. The mapping from vendored directory to output library name is:

Vendored Directory	Output Static Library Target
`fastpforlib`	`duckdb_fastpforlib`
`fmt`	`duckdb_fmt`
`fsst`	`duckdb_fsst`
`hyperloglog`	`duckdb_hyperloglog`
`libpg_query`	`duckdb_pg_query`
`mbedtls`	`duckdb_mbedtls`
`miniz`	`duckdb_miniz`
`re2`	`duckdb_re2`
`skiplist`	`duckdb_skiplistlib`
`utf8proc`	`duckdb_utf8proc`
`yyjson`	`duckdb_yyjson`
`zstd`	`duckdb_zstd`

All output static libraries are placed in the build output tree under build/<variant>/third_party/<NAME>/.

Usage Examples

Adding a New Vendored Dependency

To add a new vendored library called newlib:

Place the library source under third_party/newlib/.
Create third_party/newlib/CMakeLists.txt defining a static library target:

add_library(duckdb_newlib STATIC
    src/newlib.cpp
)
target_include_directories(duckdb_newlib PUBLIC include)

Add the invocation in the root CMakeLists.txt alongside the other third-party libraries:

add_third_party(newlib)

Link the new static library to the DuckDB target:

target_link_libraries(duckdb PUBLIC duckdb_newlib)

Inspecting the Build Graph

After configuring the project, the third-party targets are visible in the build graph:

# Configure
cmake -G Ninja -DCMAKE_BUILD_TYPE=Release -B build/release

# List all targets (Ninja)
ninja -C build/release -t targets | grep duckdb_

Expected output (excerpt):

duckdb_fastpforlib: STATIC_LIBRARY
duckdb_fmt: STATIC_LIBRARY
duckdb_fsst: STATIC_LIBRARY
duckdb_hyperloglog: STATIC_LIBRARY
duckdb_pg_query: STATIC_LIBRARY
duckdb_mbedtls: STATIC_LIBRARY
duckdb_miniz: STATIC_LIBRARY
duckdb_re2: STATIC_LIBRARY
duckdb_skiplistlib: STATIC_LIBRARY
duckdb_utf8proc: STATIC_LIBRARY
duckdb_yyjson: STATIC_LIBRARY
duckdb_zstd: STATIC_LIBRARY

Building Only the Third-Party Libraries

Individual third-party targets can be built in isolation for testing or debugging:

# Build only the re2 static library
cmake --build build/release --target duckdb_re2

# Build only the PostgreSQL query parser
cmake --build build/release --target duckdb_pg_query

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