Replace clickhouse-cpp with clickhouse-c

[serprex]

Wraps clickhouse-c in C++ exporter interface,
relying on PG MemoryContext, but with NO_OOM avoiding longjmp in C++ contexts

Avoid more allocations by not recreating columns on each batch

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Note

High Risk
Large rewrite of the bgworker ClickHouse export path (sockets, TLS, protocol, memory) plus dependency and CI changes; regressions could drop or corrupt telemetry or stall the worker on I/O.

Overview
Replaces clickhouse-cpp (vcpkg overlay port) with the vendored clickhouse-c submodule: a single CHC_IMPLEMENTATION TU, CMake links lz4/zstd/OpenSSL directly, and the ClickHouse exporter is rewritten to use native protocol I/O (POSIX or OpenSSL), LZ4 compression, chc_block_builder INSERTs, and PostgreSQL MemoryContext allocators with MCXT_ALLOC_NO_OOM so OOM does not longjmp through C++.

Batching behavior changes: column objects are created once and Clear() on each batch instead of rebuilding clickhouse-cpp blocks/columns every flush. Connection setup adds bounded TCP connect, read deadlines, and TLS (SNI, verify or skip per GUC) with cancel checks tied to ProcDiePending.

CI and local tests now init the clickhouse-c submodule, bump several GitHub Actions, drop overlay-port cache keys, and start ClickHouse with generated self-signed TLS (docker-compose.tls.yml, generate-certs.sh). New TAP t/013_clickhouse_tls.pl and psch_init_node_with_clickhouse TLS GUCs exercise encrypted export and reconnect; ClickHouse integration runs match t/*clickhouse*.pl.

Docs, Makefile, and Docker builds are updated for the new dependency layout; FindClickHouseCpp and the clickhouse-cpp overlay are removed.

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[Copilot]

Pull request overview

This PR migrates the ClickHouse export backend from the clickhouse-cpp client to the vendored, header-only clickhouse-c library, integrating it behind the existing C++ StatsExporter interface while using PostgreSQL MemoryContext allocation (with MCXT_ALLOC_NO_OOM) to avoid longjmp across C++ frames and to reuse column buffers between batches.

Changes:

• Replaced the ClickHouse exporter implementation to use clickhouse-c (native protocol, custom TCP/TLS + bounded I/O) and added a single CHC_IMPLEMENTATION translation unit.
• Updated build/dependency plumbing: removed clickhouse-cpp vcpkg overlay port and added explicit lz4/openssl dependencies and linking.
• Updated docs, CI, and quickstart scripts to initialize the new third_party/clickhouse-c submodule.

Reviewed changes

Copilot reviewed 24 out of 24 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
vcpkg.json	Drops clickhouse-cpp dependency; adds lz4/openssl alongside zstd.
vcpkg-configuration.json	Removes overlay-ports usage (keeps overlay triplets).
src/export/stats_exporter.cc	Removes clickhouse-cpp include; updates shutdown comment to reflect remaining destructor risk.
src/export/exporter_interface.h	Adds BasicColumn::Clear() hook to enable per-batch buffer reuse.
src/export/clickhouse_exporter.cc	Reimplements ClickHouse exporter using clickhouse-c, PG allocators, custom TCP/TLS connect, and binary INSERT flow.
src/export/clickhouse_c_impl.c	Adds the single CHC_IMPLEMENTATION compilation unit for clickhouse-c.
scripts/quickstart.sh	Ensures clickhouse-c submodule is initialized before building the Docker stack.
README.md	Updates dependency note from clickhouse-cpp to clickhouse-c.
Makefile	Updates build flow to ensure clickhouse-c submodule is present and uses CMake build/install.
INSTALL.md	Updates documentation to reference clickhouse-c as statically linked dependency.
docker/postgres-ext.Dockerfile	Copies vendored third_party/clickhouse-c into the build context; removes overlay-ports copy.
CMakeLists.txt	Removes ClickHouseCpp find/link; adds lz4/zstd find + links; adds SYSTEM include for vendored clickhouse-c.
cmake/FindClickHouseCpp.cmake	Removed (no longer needed).
cmake/CompilerWarnings.cmake	Updates comment to reflect exceptions/RTTI rationale (OTel/Arrow instead of clickhouse-cpp).
CLAUDE.md	Updates dependency documentation and records clickhouse-c embedding pattern and implementation TU location.
.gitmodules	Adds third_party/clickhouse-c submodule entry.
.github/workflows/release.yml	Initializes clickhouse-c submodule in release workflow.
.github/workflows/ci.yml	Initializes clickhouse-c submodule in CI jobs.
.github/workflows/ci-tap.yml	Initializes clickhouse-c submodule in TAP workflow.
.github/actions/setup-vcpkg/action.yml	Updates vcpkg cache key to stop hashing removed overlay-ports/**.
overlay-ports/clickhouse-cpp/vcpkg.json	Removed obsolete vcpkg overlay port definition.
overlay-ports/clickhouse-cpp/portfile.cmake	Removed obsolete vcpkg overlay port build script.
overlay-ports/clickhouse-cpp/fix-deps-and-build-type.patch	Removed obsolete overlay patch.

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[Copilot]

Pull request overview

Copilot reviewed 31 out of 33 changed files in this pull request and generated 1 comment.

[theory]

Yay!

[Copilot]

Pull request overview

Copilot reviewed 31 out of 33 changed files in this pull request and generated 4 comments.

[Copilot]

Pull request overview

Copilot reviewed 31 out of 33 changed files in this pull request and generated 2 comments.

[cursor]

Cursor Bugbot has reviewed your changes using default effort and found 1 potential issue.

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[Copilot]

Pull request overview

Copilot reviewed 31 out of 33 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (1)

docker/docker-compose.tls.yml:10

• This file overrides the ClickHouse service healthcheck from docker-compose.test.yml, but it omits interval, timeout, and retries. Docker Compose will fall back to much slower defaults (e.g. 30s interval), which can make docker compose up --wait noticeably slower or flaky in CI/local test runs.

Consider copying the base healthcheck timing parameters here so enabling TLS doesn’t change startup/health semantics.

    healthcheck:
      test: ["CMD", "clickhouse-client", "--secure", "--host", "localhost", "--port", "9440", "--accept-invalid-certificate", "-q", "SELECT 1"]