I dug back through our design docs from when we designed this, and we largely chose not to use Cloud Spanner due to unknowns. We were more confident we could pr

I dug back through our design docs from when we designed this, and we largely chose not to use Cloud Spanner due to unknowns. We were more confident we could predict the read and write performance in BigTable (especially due to the constraints you get when you drop relational features).