> To enable PostgreSQL tools that don’t know anything about Spanner, the PostgreSQL interface also includes an open-source adapter that runs as a sidecar proxy,

> To enable PostgreSQL tools that don’t know anything about Spanner, the PostgreSQL interface also includes an open-source adapter that runs as a sidecar proxy, close to a client. I wonder why they decided to do this instead of building a postgres-compatible endpoint into the spanner service itself.