"Spanner - Google's Distributed Database" by Sebastian Kanthak (2013)

Spanner is Google's planet-scale distributed database. Spanner partitions and replicates data across thousands of servers. Nevertheless, it provides many features known from traditional databases such as transactions over arbitrary data, a familiar row/column based data model, and support for SQL queries.
After a short overview of the system, this talk will dive into the details of how Spanner relies on GPS and atomic clocks to provide two of its most innovative features: Lock-free strong (current) reads and global snapshots that are consistent with external events.
Sebastian Kanthak
Google
Sebastian is a software engineer at Google working on Spanner, Google's planet-scale distributed database. He leads the paxos & concurrency team that deals with replication, transactions, and other concurrency modes.
Recorded at Strange Loop conference (thestrangeloop.com) in St. Louis, MO, Oct 2013.

[@akashnakka]

what is the weight of snapshot of DB sharing across multiple DC and each time sharing that to be in sync doesn't it effect the efficiency of system.