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vgi-c++

The C++ worker SDK for VGI (Vector Gateway Interface) — write DuckDB functions and catalogs in C++, ship them as one binary, no DuckDB extension to compile and no version coupling.

A worker is an ordinary binary that DuckDB launches and talks to over Apache Arrow IPC. It can expose scalar / table / aggregate functions and whole catalogs that behave like native DuckDB objects. This repo is the C++ sibling of the Rust and Python SDKs, and is built on the C++ vgi-rpc port.

The example worker passes the VGI integration suite in vgi over the subprocess transport. What is and is not implemented is written down in docs/roadmap.md, and the suite — not that file — is the specification.

Build

git clone https://github.com/Query-farm/vgi-rpc-cpp.git ../vgi-rpc-c++
export VCPKG_ROOT=/path/to/vcpkg

cmake --preset default   # Debug + tests
cmake --build build
ctest --test-dir build

vgi-rpc-c++ is built from a sibling checkout by default, since the two move together and an installed copy goes stale silently. Override with -DVGI_RPC_SOURCE_DIR=<path>, or use an installed copy with -DVGI_USE_INSTALLED_RPC=ON.

Note for Linux and macOS: vcpkg builds libsodium through its autotools script, so autoconf and automake need to be installed. Windows uses MSBuild and needs neither.

A worker

#include <vgi/worker.h>

class UpperCase : public vgi::ScalarFunction {
    std::string name() const override { return "upper_case"; }
    vgi::FunctionMetadata metadata() const override {
        vgi::FunctionMetadata md;
        md.return_type = arrow::utf8();
        return md;
    }
    std::vector<vgi::ArgSpec> argument_specs() const override {
        return {vgi::ArgSpec::column("value", 0, "varchar")};
    }
    std::shared_ptr<arrow::RecordBatch> process(
        const vgi::ProcessParams& params,
        const std::shared_ptr<arrow::RecordBatch>& batch) const override;
};

int main(int argc, char** argv) {
    vgi::Worker worker;
    worker.register_scalar(std::make_shared<UpperCase>());
    worker.run(argc, argv);  // stdio, --unix <path>, or --http
}

example-worker/ is the full fixture set the integration suite runs against — several hundred functions across every shape the protocol has, and the best place to look for how any one of them is meant to behave.

Running the suite

scripts/run_tests.sh                 # the whole in-scope suite
scripts/run_tests.sh scalar          # one category
scripts/run_tests.sh test/sql/integration/scalar/upper_case.test

It drives ~/Development/vgi's unittest binary against the release worker. VGI_EXT points at the extension checkout, VGI_CPP_BUILD at the build directory, and VGI_CPP_TEST_CACHE at a scratch directory — the last matters when two runs go at once, since they would otherwise share one log.

Licence

Query Farm Source-Available License, Version 1.0 — see LICENSE. The same licence as vgi-python and the DuckDB extension.