Compatibility Matrix

For engineers checking whether PostgreSQL clients and protocol behaviors are covered before a rollout.

pg-kinetic keeps a cross-language compatibility matrix for PostgreSQL clients. The matrix can run the same behavior contract against direct PostgreSQL and pg-kinetic so reports can compare proxy behavior with the baseline server path.

The stable 1.0 support boundary is defined in the Stable 1.0 Release Contract. It covers PostgreSQL 16 and 18 as tested release targets; other server versions require a matching compatibility run before a support claim is made.

Current Compatibility Status

Area	Status
PostgreSQL server versions	Tested only where the local compatibility or CI stack starts PostgreSQL. Do not infer broad version coverage from docs alone.
Simple query protocol	Covered by smoke checks.
Extended query protocol	Covered by prepared-query smoke checks where each driver suite supports it.
Cancellation requests	Supported for bound backends; unknown cancel keys are dropped silently.
Backend parameter status	Captured from backend startup and replayed to clients on pooled connection reuse.
COPY, LISTEN/NOTIFY, temp tables, advisory locks	Treated as stateful or pinning-sensitive behavior; not broad compatibility guarantees.
Sharding and policy-denial cases	Preview/opt-in only; not default live proxy compatibility.

Protocol Details

Cancellation

PostgreSQL cancellation uses a separate startup packet containing a process id and secret key. pg-kinetic issues client-facing cancel keys during startup, binds them to the currently checked-out backend key while a backend is assigned, and forwards cancellation by opening a backend cancel connection with the backend's own process id and secret key.

If the cancel key is unknown or no backend target is currently bound, pg-kinetic drops the cancel request without surfacing an error to the canceling connection. This matches the PostgreSQL cancellation shape where the cancel connection is not the query connection.

server_version And Parameter Status

pg-kinetic forwards backend ParameterStatus fields such as server_version, client_encoding, and standard_conforming_strings to the client. When a pooled backend is reused, the proxy replays the captured parameter status in the synthetic startup-ready response so clients still see the backend parameters they expect.

Do not use server_version as a broad compatibility guarantee by itself. The release contract names the PostgreSQL versions covered by the current validation matrix; clients can observe a backend-reported version even when that exact version has not been promoted to a documented support target.

Libraries

Language	Libraries
Rust	tokio-postgres, sqlx, optional diesel
Go	pgx, database/sql through the pgx stdlib adapter
Java	JDBC DriverManager, PostgreSQL DataSource, HikariCP, Spring JDBC, optional Spring Boot DataSource, optional jOOQ
JavaScript and TypeScript	pg, Prisma where available, Kysely
Python	psycopg 3, asyncpg, SQLAlchemy
PHP	PDO PostgreSQL, pgsql, framework database layers that use the PostgreSQL protocol
.NET	Npgsql, optional EF Core provider
C	libpq
C++	optional libpqxx

Optional suites keep their build files in the tree and report a structured skip when the local toolchain or system library is not available.

Local Commands

List configured suites:

cargo run -p xtask -- compat --list

Run smoke suites for each target:

cargo run -p xtask -- compat --target direct-postgres --smoke
cargo run -p xtask -- compat --target pg-kinetic --smoke

Run a language-specific check:

cargo run -p xtask -- compat --language java --target pg-kinetic

PowerShell parity:

powershell.exe -ExecutionPolicy Bypass -File scripts\compat\run.ps1 -Language java -Target pg-kinetic

Live Runs

Structural report generation does not require a database. Live suite execution requires both target services and explicit opt-in:

docker compose -f bench/compose.yml up -d --build pg-direct pg-kinetic
export PG_KINETIC_COMPAT_LIVE=1
export PG_KINETIC_COMPAT_SERVICES=direct-postgres,pg-kinetic
export DATABASE_URL_DIRECT=postgres://postgres:postgres@127.0.0.1:55432/pgkinetic
export DATABASE_URL_PROXY=postgres://postgres:postgres@127.0.0.1:58432/pgkinetic
psql "$DATABASE_URL_DIRECT" -f compat/common/schema.sql
psql "$DATABASE_URL_DIRECT" -f compat/common/seed.sql
psql "$DATABASE_URL_PROXY" -f compat/common/schema.sql
psql "$DATABASE_URL_PROXY" -f compat/common/seed.sql
cargo run -p xtask -- compat --language rust --target pg-kinetic

Use DATABASE_URL_DIRECT and DATABASE_URL_PROXY for suite-level connection strings when a language runner needs a non-default address.

Reports

Every suite emits normalized JSON with the stable fields language, library, version, target, outcome, skip_reason, and error_summary. Reports may also include duration_ms and suite-specific case details. Missing toolchains, unavailable services, and unsupported library features are skip outcomes with stable reasons; they are never converted to synthetic passes.

Large per-suite artifacts are written only under target/compat/, which is ignored by Git.

CI

Pull requests start the local PostgreSQL and pg-kinetic stack, load the shared fixtures, and run each language smoke matrix against both direct PostgreSQL and pg-kinetic. Manual and scheduled compatibility jobs also select the framework category for heavier Spring-style coverage.

Behavior Contract

compat/common/contract.toml defines the shared cases:

• connection startup
• simple and parameterized queries
• prepared statements and invalidation
• commit and rollback
• pool reuse
• server error propagation
• TLS and authentication paths
• read routing and primary writes
• preview-only sharding and policy-denial cases when explicitly selected

Advanced cases require matching local pg-kinetic configuration and remain opt-in so the default smoke matrix stays bounded.

Adding A Library

Add the language project files under compat/<language>/, register a compatibility entry in regression/manifest.toml, and keep reports in the normalized shape. Required libraries must have direct PostgreSQL and pg-kinetic coverage unless the library only exposes behavior through a framework wrapper.