Spanner: Google's Globally Distributed Database

Spanner: Database that shards data across many set of Paxos state machines in data centers spread accross the world.

Time API

Sawtooth peak when executing, comes back when synced from server.

Smax: largest timestamp till relpica is up to date.

Leases

leaders participate in local and distributed transactions. So it's better to have leaders for long time. Auto released after expiration.

extend the lease: - leader can ssign timestamp to lease in future. - leader can try to extend it's lease to make sure it's present when transaction happens.

Snapshot isolation: all reads satisfied from the image.

• not as strong as strict serializability.
• supported using Tsafe -> time when you don't have prepare transactions.