2. What is Megastore?
● A storage system developed by Google to meet the
requirements of today's interactive online services
● Blends the scalability of a NoSQL datastore with
the convenience of a traditional RDBMS
○ Bigtable for logs and data
○ Modified Paxos Logic for ACID
● Provides both consistency guarantees and high availability
● Provides fully serializable ACID semantics within fine-
grained partitions of data
4. Entity Groups
Example Cross Entity Group
Application Entity Groups
Operations
Email Account None (external to the system)
Users, Blogs,
Blogs Access Control, Notifications
Posts
Globe Divisions Operations that span multiple
Maps
(Patches) patches