C++での拡張機能の作成

-- Unqualified (preferred for cleaner code)
SELECT complex_abs(impedance) FROM signals;

-- Qualified with extension name (explicit)
SELECT vsql_complex.complex_abs(impedance) FROM signals;

cd /path/to/villagesql-source
cp -r villagesql/sdk/template my-extension
cd my-extension

{
  "$schema": "https://raw.githubusercontent.com/villagesql/villagesql-docs/main/mysql-8.4/0.0.5/manifest.json.schema.json",
  "name": "my_awesome_extension",
  "version": "1.0.0",
  "description": "My custom VillageSQL extension that does amazing things",
  "author": "Your Name",
  "license": "GPL-2.0"
}

-- manifest.json has "name": "my_awesome_extension"
INSTALL EXTENSION my_awesome_extension;  -- ✅ Correct: no quoting needed
INSTALL EXTENSION `my-awesome-extension`;  -- ⚠️ Works, but requires backtick quoting

#include <villagesql/vsql.h>

// Your implementation code here

VEF_GENERATE_ENTRY_POINTS(
  make_extension()
    .func(make_func<&my_reverse_impl>("my_reverse")
      .returns(STRING)
      .param(STRING)
      .build())
    .func(make_func<&count_vowels_impl>("count_vowels")
      .returns(INT)
      .param(STRING)
      .build())
);

void complex_conjugate_impl(CustomArg in, CustomResult out) {
    if (in.is_null()) { out.set_null(); return; }
    auto src = in.value();    // Span<const unsigned char> — raw binary
    auto dst = out.buffer();  // Span<unsigned char>
    // ... read src, write result to dst ...
    out.set_length(src.size());
}

.func(make_func<&complex_conjugate_impl>("complex_conjugate")
          .returns(COMPLEX)
          .param(COMPLEX)
          .build())

.func(make_func<&complex_add_impl>("complex_add")
          .returns(COMPLEX)
          .param(COMPLEX)
          .param(COMPLEX)
          .deterministic()
          .build())

-- Deterministic VDFs can be used in generated columns
CREATE TABLE t (
    a COMPLEX,
    b COMPLEX,
    result COMPLEX GENERATED ALWAYS AS (complex_add(a, b)) STORED
);
-- STORED vs VIRTUAL follows standard MySQL generated column rules

make_func<&large_result_impl>("large_result")
  .returns(STRING)
  .param(INT)
  .buffer_size(65536)  // Request 64KB buffer
  .build()

void large_result_impl(StringArg input, StringResult out) {
    if (input.is_null()) { out.set_null(); return; }
    size_t needed = calculate_output_size(input.value());

    auto buf = out.buffer();
    if (needed > buf.size()) {
        out.error("Output exceeds buffer size");
        return;
    }

    // Write output into buf.data()
    out.set_length(actual_output_length);
}

make_func<&large_result_impl>("large_result")
  .returns(STRING)
  .max_result_length(65536)
  .build()

cmake_minimum_required(VERSION 3.18)
project(my_extension)

# Find VillageSQL Extension Framework
find_package(VillageSQLExtensionFramework QUIET)

# The framework detects build flags via 4 methods (in order):
# 1. Explicit MYSQL_INCLUDE_FLAGS/MYSQL_CXXFLAGS
# 2. VillageSQL_BUILD_DIR (reads CMakeCache.txt from VillageSQL build)
# 3. VSQL_BASE_DIR (uses mysql_config)
# 4. Default - mysql_config from PATH

# Build shared library with your source files
add_library(extension SHARED
    src/extension.cc
    src/my_functions.cc
)

# Create VEB archive
VEF_CREATE_VEB(
    NAME my_extension
    LIBRARY_TARGET extension
    MANIFEST ${CMAKE_CURRENT_SOURCE_DIR}/manifest.json
)

# Install VEB to VillageSQL extensions directory
install(FILES ${VEB_OUTPUT} DESTINATION ${INSTALL_DIR})

mkdir build
cd build

# Configure the build
cmake ..

# Or, if building against VillageSQL source:
cmake .. -DVillageSQL_BUILD_DIR=/path/to/villagesql/build

# Or, to build against the unstable dev ABI headers:
cmake .. -DVSQL_USE_DEV_ABI=ON

# Build the extension
make

make show_veb

manifest.json
lib/myext.so

make install

# Find the VEF directory
mysql -u root -p -e "SHOW VARIABLES LIKE 'veb_dir';"

# Copy the VEB file
sudo cp my-awesome-extension.veb /path/to/veb_dir/

make show_veb
tail -f /var/log/mysql/error.log

SELECT * FROM INFORMATION_SCHEMA.EXTENSIONS;

# Verify mysql_config is available
which mysql_config
mysql_config --version

# Check compiler version
gcc --version  # or clang --version

# Verify CMake version (3.18+ required)
cmake --version