Google's game is planet scale systems. Cloud SQL is woefully inadequate, basically a single machine DB with replication. Datastore is built on Megastore, which

Google's game is planet scale systems. Cloud SQL is woefully inadequate, basically a single machine DB with replication. Datastore is built on Megastore, which is the precursor to Spanner, largely confined to a handful of nearly located datacenters [think US-East]. Google's internal data will be stored on / migrated to Spanner, I expect sooner rather than later. We'll be using Spanner whenever we'll be using Google. Furthermore, it's likely we'll use Spanner whenever we use a planet scale system built on GCP, say Spotify.