One thing to note is Spanner's transactions are different compared to what you get with a traditional RDBMS. See https://cloud.google.com/spanner/docs/transacti

One thing to note is Spanner's transactions are different compared to what you get with a traditional RDBMS. See https://cloud.google.com/spanner/docs/transactions#ro_transaction_example https://cloud.google.com/spanner/docs/transactions#ro_transa... An example is the rows you get back from a query like "select * from T where x=a" can't be part of a RW transaction. I believe because they don't have the time-stamp associated with them. So, you have to re-read those rows via primary key inside a RW transaction to update them. This can be a surprise if you are coming from a traditional RDBMS background. If you are think about porting your app from MySQL/PostgreSQL to Spanner, it will be more than just updating query syntax. Disclaimer: I used F1 (built on top of Spanner, https://research.google.com/pubs/pub41344.html https://research.google.com/pubs/pub41344.html) few years ago.