pg_grpc

Make gRPC calls directly from PostgreSQL SQL.

-- 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);

Both return:

       grpc_call
-----------------------
 {"f_string": "hello"}
(1 row)

grpc_call signature

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

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

Quickstart: stage protos and call

1. Compile protos

SELECT grpc_proto_stage('common.proto', $PROTO$
    syntax = "proto3";
    package auth;
    message UserId { string id = 1; }
    message User {
      string id = 1;
      string email = 2;
    }
$PROTO$);

SELECT grpc_proto_stage('auth.proto', $PROTO$
    syntax = "proto3";
    import "common.proto";
    package auth;
    service AuthService {
      rpc GetUser(UserId) returns (User);
    }
$PROTO$);

SELECT grpc_proto_compile();

Optional. Skip this step if your server exposes gRPC reflection — grpc_call will resolve schemas automatically.

2. Call the service

SELECT grpc_call(
    'localhost:50051',
    'auth.AuthService/GetUser',
    '{"id": "42"}'::jsonb
);

Proto management API

Function	Description
grpc_proto_stage(filename, source)	Stage a .proto file for the next compile
grpc_proto_unstage(filename)	Remove one staged file
grpc_proto_unstage_all()	Clear all staged files
grpc_proto_compile()	Parse + compile staged files
grpc_proto_unregister(service_name)	Remove one compiled service
grpc_proto_unregister_all()	Remove all compiled services
grpc_proto_list_staged()	List all staged .proto
grpc_proto_list_registered()	List all registered services

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
Proto compile error: …	grpc_proto_compile failed to parse/resolve the staged files
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 (for the reflection path) a new reflection request are made on every call
• Endpoint format — host:port, never include a scheme
• Reflection — required unless you use grpc_proto_stage + grpc_proto_compile
• Per-connection state — the staged/registered protos live inside a single Postgres backend; new connections start empty