Spanner is a globally distributed database that provides external consistency between data centers and stores data in a schema based semi-relational data structure. Not only that, Spanner provides a versioned view of the data that allows for instantaneous snapshot isolation across any segment of the data. This versioned isolation allows Spanner to provide globally consistent reads of the database at a particular time allowing for lock-free read-only transactions (and therefore no communications overhead for consensus during these types of reads). Spanner also provides externally consistent reads and writes with a timestamp-based linear execution of transactions and two phase commits. Spanner is the first distributed database that provides global sharding and replication with strong consistency semantics.