pg_grpc

Make gRPC calls directly from PostgreSQL SQL.

SELECT grpc_call('localhost:50051', 'package.Service/Method', '{"key": "value"}'::jsonb);

No .proto files or code generation needed — message schemas are resolved at runtime via gRPC server reflection.

Usage

-- named
SELECT grpc_call(
    endpoint => 'grpcb.in:9000',
    method   => 'grpcbin.GRPCBin/DummyUnary',
    request  => '{"f_string": "hello"}'::jsonb
);

-- positional
SELECT grpc_call('grpcb.in:9000', 'grpcbin.GRPCBin/DummyUnary', '{"f_string": "hello"}'::jsonb);

grpc_call signature

grpc_call(
    endpoint   TEXT,
    method     TEXT,
    request    JSONB,
    timeout_ms BIGINT DEFAULT NULL  -- accepted but not yet implemented
) RETURNS JSONB

Parameter	Description
endpoint	host:port — no scheme (e.g. localhost:50051, not http://localhost:50051)
method	package.Service/Method (e.g. grpcbin.GRPCBin/DummyUnary)
request	Request payload; field names must match proto field names

Returns the response as JSONB with proto field names (snake_case).

Errors

All errors raise a PostgreSQL ERROR and abort the current statement:

Prefix	Cause
Connection error: …	Could not reach the endpoint
Proto error: …	Reflection failed, symbol not found, or JSON ↔ protobuf encode/decode error
gRPC call failed: …	Server returned a non-OK gRPC status

Limitations

• HTTP only — TLS/mTLS not supported
• Unary only — streaming methods not supported
• No caching — a new connection and reflection request are made on every call
• Endpoint format — host:port, never include a scheme
• Reflection — server must expose grpc.reflection.v1alpha.ServerReflection