微服务，数据一致性

outbox

using var tx = db.Database.BeginTransaction();

db.Orders.Add(order);
db.OutboxMessages.Add(new OutboxMessage{
    Id = Guid.NewGuid(),
    Type = "OrderCreated",
    Payload = Json,
    Status = 0
});

db.SaveChanges();
tx.Commit();   // ≤ 10ms