Pure C. Replace clickhouse-cpp with clickhouse-c

clickhouse-c is an experimental clickhouse library focused on minimalism,
allowing for proper compatibility reusing postgres allocator

Author: serprex

.github/workflows/bake.yml

@@ -29,11 +29,6 @@ jobs:
           registry: ghcr.io
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
-      - name: Cache Vendor Build
-        uses: actions/cache@v4
-        with:
-          path: vendor/_build
-          key: ${{ runner.os }}-vendor-build
       - name: Set Bake Variables
         run: make bake-vars REGISTRY=ghcr.io/clickhouse PG_VERSIONS=${{ matrix.pgv }} >> $GITHUB_ENV
       - name: Build${{ startsWith(github.ref, 'refs/tags') && ' and Push' || '' }}

.github/workflows/clickhouse.yml

@@ -27,7 +27,7 @@ jobs:
     container: pgxn/pgxn-tools
     steps:
       - name: Start Postgres
-        run: pg-start ${{ env.pg }} libcurl4-openssl-dev uuid-dev libre2-dev
+        run: pg-start ${{ env.pg }} libcurl4-openssl-dev uuid-dev liblz4-dev libzstd-dev libre2-dev
       - name: Install Extensions
         run: pgxn install re2
       - name: Checkout the Repository
@@ -36,19 +36,5 @@ jobs:
       - name: Start ClickHouse
         env: { CH_RELEASE: "${{ matrix.ch }}" }
         run: .github/ubuntu/clickhouse.sh
-      - name: Cache Dependencies
-        uses: actions/cache@v5
-        with:
-          path: vendor/_build/*
-          key: vendor-${{ runner.os }}-${{ runner.arch }}-${{ hashFiles('.git/modules/clickhouse-cpp/refs/heads/master') }}
-      # Required to prevent clickhouse-cpp from rebuilding because it depends
-      # on this file in the Makefile. https://github.com/actions/checkout/issues/968
-      - name: Reset Vendor Timestamp
-        run: cd vendor/clickhouse-cpp && touch -d $(git log -1 --format="@%ct" CMakeLists.txt) CMakeLists.txt
-      - name: Test DSO
+      - name: Test
         run: pg-build-test
-      - name: Clean
-        run: make clean NO_VENDOR_CLEAN=1
-      - name: Test Static
-        run: pg-build-test
-        env: { CH_BUILD: static }

.github/workflows/lint.yml

@@ -14,7 +14,7 @@ jobs:
     env: { pg: 18 }
     steps:
       - name: Install Postgres
-        run: NO_CLUSTER=1 pg-start ${{ env.pg }} libcurl4-openssl-dev uuid-dev clang-tidy
+        run: NO_CLUSTER=1 pg-start ${{ env.pg }} libcurl4-openssl-dev uuid-dev liblz4-dev libzstd-dev clang-tidy
       - name: Install clang-format # version in Ubuntu is too old
         run: curl -sLo /usr/local/bin/clang-format https://github.com/cpp-linter/clang-tools-static-binaries/releases/latest/download/clang-format-22_linux-amd64 && chmod +x /usr/local/bin/clang-format
       - name: Checkout the Repository

.github/workflows/postgres.yml

@@ -19,27 +19,13 @@ jobs:
     container: pgxn/pgxn-tools
     steps:
       - name: Start Postgres ${{ matrix.pg }}
-        run: pg-start ${{ matrix.pg }} libcurl4-openssl-dev uuid-dev libre2-dev
+        run: pg-start ${{ matrix.pg }} libcurl4-openssl-dev uuid-dev liblz4-dev libzstd-dev libre2-dev
       - name: Install Extensions
         run: pgxn install re2
       - name: Checkout the Repository
         uses: actions/checkout@v6
         with: { submodules: true }
       - name: Start ClickHouse
         run: .github/ubuntu/clickhouse.sh
-      - name: Cache Dependencies
-        uses: actions/cache@v5
-        with:
-          path: vendor/_build/*
-          key: vendor-${{ runner.os }}-${{ runner.arch }}-${{ hashFiles('.git/modules/clickhouse-cpp/refs/heads/master') }}
-      # Required to prevent clickhouse-cpp from rebuilding because it depends
-      # on this file in the Makefile. https://github.com/actions/checkout/issues/968
-      - name: Reset Vendor Timestamp
-        run: cd vendor/clickhouse-cpp && touch -d $(git log -1 --format="@%ct" CMakeLists.txt) CMakeLists.txt
-      - name: Test DSO
+      - name: Test
         run: pg-build-test
-      - name: Clean
-        run: make clean NO_VENDOR_CLEAN=1
-      - name: Test Static
-        run: pg-build-test
-        env: { CH_BUILD: static }

.github/workflows/release.yml

@@ -15,7 +15,7 @@ jobs:
       - name: Check out the repo
         uses: actions/checkout@v6
       - name: Start Postgres
-        run: pg-start 18 libcurl4-openssl-dev uuid-dev
+        run: pg-start 18 libcurl4-openssl-dev uuid-dev liblz4-dev libzstd-dev
       - name: Start ClickHouse
         env: { CH_RELEASE: "${{ matrix.ch }}" }
         run: .github/ubuntu/clickhouse.sh

.gitmodules

@@ -1,3 +1,3 @@
-[submodule "clickhouse-cpp"]
-	path = vendor/clickhouse-cpp
-	url = https://github.com/ClickHouse/clickhouse-cpp.git
+[submodule "vendor/clickhouse-c"]
+	path = vendor/clickhouse-c
+	url = https://github.com/ClickHouse/clickhouse-c

CHANGELOG.md

@@ -11,6 +11,9 @@ All notable changes to this project will be documented in this file. It uses the
 
 ### ⚡ Improvements
 
+*   Replaced the `clickhouse-cpp` driver with [ClickHouse/clickhouse-c],
+    pulled in as a git submodule under `vendor/clickhouse-c`.
+
 *   Added multidimensional array support across SELECT and INSERT to both the
     binary and http drivers. Rectangular ClickHouse `Array(Array(...))` values
     now map to PostgreSQL multidimensional arrays, jagged arrays not supported,
@@ -21,6 +24,7 @@ All notable changes to this project will be documented in this file. It uses the
   [v0.3.1]: https://github.com/ClickHouse/pg_clickhouse/compare/v0.3.0...v0.3.1
   [#233]: https://github.com/ClickHouse/pg_clickhouse/pull/233
     "ClickHouse/pg_clickhouse#233 Support multidimensional arrays"
+  [ClickHouse/clickhouse-c]: https://github.com/ClickHouse/clickhouse-c
 
 ## [v0.3.0] — 2026-05-11
 

Dockerfile

@@ -11,6 +11,8 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     make \
     cmake \
     libssl-dev \
+    liblz4-dev \
+    libzstd-dev \
     libre2-dev \
     pgxnclient \
     unzip \
@@ -24,7 +26,7 @@ RUN cd /tmp && pgxn download re2 && unzip re2-*.zip && rm re2-*.zip && cd re2-*
 FROM postgres:$PG_MAJOR-trixie
 
 # Install dependencies
-RUN apt-get update && apt-get install -y --no-install-recommends libcurl4t64 uuid libre2-11 ca-certificates \
+RUN apt-get update && apt-get install -y --no-install-recommends libcurl4t64 uuid libre2-11 liblz4-1 libzstd1 ca-certificates \
     && apt-get clean \
     && rm -rf /var/cache/apt/* /var/lib/apt/lists/*
 

Makefile

@@ -16,97 +16,38 @@ CURL_CONFIG ?= curl-config
 OS 	        ?= $(shell uname -s | tr A-Z a-z)
 ARCH         = $(shell uname -m)
 
-# Collect all the C++ and C files to compile into MODULE_big.
-OBJS = $(subst .cpp,.o, $(wildcard src/*.cpp src/*/*.cpp)) \
-       $(subst .c,.o, $(wildcard src/*.c src/*/*.c))
-
-# Build static on Darwin by default.
-ifndef CH_BUILD
-# ifeq ($(OS),darwin)
-	CH_BUILD = static
-# else
-# 	CH_BUILD = dynamic
-# endif
-endif
+# Collect all the C files to compile into MODULE_big.
+OBJS = $(subst .c,.o, $(wildcard src/*.c src/*/*.c))
 
-# clickhouse-cpp source and build directories.
-CH_CPP_DIR = vendor/clickhouse-cpp
-CH_CPP_BUILD_DIR = vendor/_build/$(OS)-$(ARCH)-$(CH_BUILD)-$(shell git submodule status $(CH_CPP_DIR) | awk '{print substr($$1, 0, 7)}')
-
-# List the clickhouse-cpp libraries we require.
-CH_CPP_LIB = $(CH_CPP_BUILD_DIR)/clickhouse/libclickhouse-cpp-lib$(DLSUFFIX)
-CH_CPP_FLAGS = -D CMAKE_BUILD_TYPE=Release -D WITH_OPENSSL=ON
-
-# Are we statically compiling clickhouse-cpp into the extension or no?
-ifeq ($(CH_BUILD), static)
-# We'll need all the clickhouse-cpp static libraries.
-	CH_CPP_LIB = $(CH_CPP_BUILD_DIR)/clickhouse/libclickhouse-cpp-lib.a
-	SHLIB_LINK = $(CH_CPP_LIB) \
-	  $(CH_CPP_BUILD_DIR)/contrib/cityhash/cityhash/libcityhash.a \
-	  $(CH_CPP_BUILD_DIR)/contrib/absl/absl/libabsl_int128.a \
-	  $(CH_CPP_BUILD_DIR)/contrib/lz4/lz4/liblz4.a \
-	  $(CH_CPP_BUILD_DIR)/contrib/zstd/zstd/libzstdstatic.a
-else
-#   Build and install the shared library.
-	SHLIB_LINK = -L$(CH_CPP_BUILD_DIR)/clickhouse -lclickhouse-cpp-lib
-	CH_CPP_FLAGS += -D BUILD_SHARED_LIBS=ON
-endif
+# clickhouse-c is a header-only single-header library. Override
+# CH_C_DIR to point elsewhere when developing against a local checkout.
+CH_C_DIR ?= vendor/clickhouse-c
 
 # Add include directories.
-PG_CPPFLAGS = -I./src/include -I$(CH_CPP_DIR) -I$(CH_CPP_DIR)/contrib/absl
-
-# Include other libraries compiled into clickhouse-cpp.
-PG_LDFLAGS = -lstdc++ -lssl -lcrypto $(shell $(CURL_CONFIG) --libs)
+PG_CPPFLAGS = -I./src/include -I$(CH_C_DIR)
 
-# clickhouse-cpp requires C++ v17.
-PG_CXXFLAGS = -std=c++17
-
-# Suppress annoying pre-c99 warning and include curl flags.
-PG_CFLAGS = -Wno-declaration-after-statement -Werror=type-limits $(shell $(CURL_CONFIG) --cflags)
+# Link OpenSSL (for TLS in the binary driver), curl (for the HTTP driver),
+# libuuid (for http_streaming.c's query-id generator), and lz4 / zstd
+# (for the binary driver's compressed-frame codecs).
+PG_LDFLAGS = -lssl -lcrypto -llz4 -lzstd $(shell $(CURL_CONFIG) --libs)
 
-# We'll need libuuid except on darwin, where it's included in the OS.
+# libuuid is provided by the OS on darwin; explicit link elsewhere.
 ifneq ($(OS),darwin)
 	PG_LDFLAGS += -luuid
 endif
 
-# Clean up the clickhouse-cpp build directory and generated files.
+# Suppress annoying pre-c99 warning and include curl flags.
+PG_CFLAGS = -Wno-declaration-after-statement -Werror=type-limits $(shell $(CURL_CONFIG) --cflags)
+
+# Clean up generated files.
 EXTRA_CLEAN = sql/$(EXTENSION)--$(EXTVERSION).sql src/include/version.h compile_commands.json test/schedule $(EXTENSION)-$(DISTVERSION).zip
-ifndef NO_VENDOR_CLEAN
-	EXTRA_CLEAN += $(CH_CPP_BUILD_DIR)
-endif
 
 # Import PGXS.
 PGXS := $(shell $(PG_CONFIG) --pgxs)
 include $(PGXS)
 
-# We'll need the clickhouse-cpp library and rpath so it can be found.
-SHLIB_LINK += -Wl,-rpath,$(pkglibdir)/
-
-# PostgreSQL 15 and earlier violate a C++ v17 storage specifier error.
-ifeq ($(shell test $(MAJORVERSION) -lt 16; echo $$?),0)
-	PG_CXXFLAGS += -Wno-register
-endif
-
-# Add the flags to the bitcode compiler variables.
-COMPILE.cc.bc += $(PG_CPPFLAGS)
-COMPILE.cxx.bc += $(PG_CXXFLAGS)
-
-# shlib is the final output product: clickhouse-cpp and all .o dependencies.
-$(shlib): $(CH_CPP_LIB) $(OBJS)
-
-# Clone clickhouse-cpp submodule.
-$(CH_CPP_DIR)/CMakeLists.txt:
-	git submodule update --init
-
-# Require the vendored clickhouse-cpp and the version header.
-$(OBJS): $(CH_CPP_LIB) src/include/version.h
-
-# Build clickhouse-cpp.
-$(CH_CPP_LIB): export CXXFLAGS=-fPIC
-$(CH_CPP_LIB): export CFLAGS=-fPIC
-$(CH_CPP_LIB): $(CH_CPP_DIR)/CMakeLists.txt # Sync with "Reset Vendor Timestamp" steps in workflows.
-	cmake -B $(CH_CPP_BUILD_DIR) -S $(CH_CPP_DIR) $(CH_CPP_FLAGS) -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
-	cmake --build $(CH_CPP_BUILD_DIR) --parallel $$(nproc) --target all
+# Require the version header.
+$(OBJS): src/include/version.h
 
 # Require the versioned C source and SQL script.
 all: sql/$(EXTENSION)--$(EXTVERSION).sql
@@ -119,17 +60,6 @@ sql/$(EXTENSION)--$(EXTVERSION).sql: sql/$(EXTENSION).sql
 src/include/version.h: src/include/version.h.in
 	sed -e 's,__VERSION__,$(DISTVERSION),g' $< > $@
 
-# Configure install/uninstall of the clickhouse-cpp library.
-ifneq ($(CH_BUILD), static)
-# Copy all dynamic files; use -a to preserve symlinks.
-install-ch-cpp: $(CH_CPP_LIB) $(shlib)
-	cp -a $(CH_CPP_BUILD_DIR)/clickhouse/libclickhouse-cpp-lib*$(DLSUFFIX)* $(DESTDIR)$(pkglibdir)/
-uninstall-ch-cpp:
-	rm -f $(DESTDIR)$(pkglibdir)/libclickhouse-cpp-lib*$(DLSUFFIX)*
-install: install-ch-cpp
-uninstall: uninstall-ch-cpp
-endif
-
 # Build a PGXN distribution bundle.
 dist: $(EXTENSION)-$(DISTVERSION).zip
 
@@ -187,7 +117,7 @@ bake-vars:
 	@echo "revision=$(REVISION)"
 	@echo "pg_versions=$(PG_VERSIONS)"
 
-# Format the .c, .h, and .hh files according to the PostgreSQL indentation
+# Format the .c and .h files according to the PostgreSQL indentation
 # standard. Requires `pg_bsd_indent` to be in the path.
 indent: dev/indent.sh
 	@$<
@@ -199,7 +129,7 @@ lint: .pre-commit-config.yaml
 
 .PHONY: clang-tidy # Run clang-tidy static analysis (requires compile_commands.json)
 clang-tidy: compile_commands.json
-	clang-tidy -p . $(wildcard src/*.c src/*.cpp)
+	clang-tidy -p . $(wildcard src/*.c)
 
 ## .git/hooks/pre-commit: Install the pre-commit hook
 .git/hooks/pre-commit:
@@ -216,8 +146,8 @@ lsp: compile_commands.json
 
 # Requires https://github.com/rizsotto/Bear.
 compile_commands.json:
-	$(MAKE) clean -j $$(nproc) NO_VENDOR_CLEAN=$(NO_VENDOR_CLEAN)
-	bear -- $(MAKE) all -j $$(nproc) NO_VENDOR_CLEAN=$(NO_VENDOR_CLEAN)
+	$(MAKE) clean -j $$(nproc)
+	bear -- $(MAKE) all -j $$(nproc)
 
 # ClickHouse Docker Containers
 start-containers: dev/Makefile dev/docker-compose.yml

README.md

@@ -82,8 +82,7 @@ sudo apt install \
   uuid-dev \
   libssl-dev \
   make \
-  cmake \
-  g++
+  gcc
 ```
 
 #### RedHat / CentOS / Yum
@@ -95,7 +94,6 @@ sudo yum install \
   libuuid-devel \
   openssl-libs \
   automake \
-  cmake \
   gcc
 ```
 
@@ -121,18 +119,6 @@ make
 sudo make install
 ```
 
-<!-- XXX DSO currently disabled.
-By default `make` dynamically links the `clickhouse-cpp` library (except on
-macOS, where a dynamic `clickhouse-cpp` library is not yet supported). To
-statically compile the ClickHouse library into `pg_clickhouse`, pass
-`CH_BUILD=static`:
-
-```sh
-make CH_BUILD=static
-sudo make install CH_BUILD=static
-```
- -->
-
 If your host has several PostgreSQL installations, you might need to specify
 the appropriate version of `pg_config`:
 
@@ -239,8 +225,8 @@ CREATE EXTENSION pg_clickhouse SCHEMA env;
 ## Dependencies
 
 The `pg_clickhouse` extension requires [PostgreSQL] 13 or higher, [libcurl],
-[libuuid]. Building the extension requires a C and C++ compiler, [libSSL], [GNU
-make], and [CMake].
+[libuuid]. Building the extension requires a C compiler, [libSSL], and [GNU
+make].
 
 ## Road Map
 
@@ -295,7 +281,6 @@ adding DML features. Our road map:
   [libcurl]: https://curl.se/libcurl/ "libcurl — your network transfer library"
   [libuuid]: https://linux.die.net/man/3/libuuid "libuuid - DCE compatible Universally Unique Identifier library"
   [GNU make]: https://www.gnu.org/software/make "GNU Make"
-  [CMake]: https://cmake.org/ "CMake: A Powerful Software Build System"
   [LibSSL]: https://openssl-library.org "OpenSSL Library"
   [TPC-H]: https://www.tpc.org/tpch/
   [re2]: https://github.com/ClickHouse/pg_re2 "pg_re2: ClickHouse-compatible regex functions using RE2"