DistOS 2015W Session 11

BigTable

• Google System used for storing data of various Google Products, for instance Google Analytics, Google Finance, Orkut, Personalized Search, Writely, Google Earth and many more
• Big table is
  • Sparse
  • Persistant
  • Muti dimensional Sorted Map
• It is indexed by
  • Row Key: Every read or write of data under single row key is atomic. Each row range is called Tablet. Select Row key to get good locality for data access.
  • Column Key: Grouped into sets called Column Families. Forms basic unit of Access Control.All data stored is of same type.Syntax used: family:qualifier
  • Time Stamp:Each cell consists of multiple versions of same data which are indexed by Timestamps.In order to avoid collisions, Timestamps need to be generated by applications.
• Big Table API: Provides functions for
  • Creating and Deleting
    • Tables
    • Column Families
  • Changing Cluster
  • Changing Table
  • Column Family metadata like Access Control Rights.
  • Set of wrappers which allow Big Data to be used both as
    • Input source
    • Output Target

Dynamo

• Availability is the buzz word for Dynamo. Dynamo=Availability
• Shifted Computer Science paradigm from caring about the consistency to availability.
• Sacrifices consistency under certain failure scenarios.
• Treats failure handling as normal case without impact on availability and performance.
• Data is partitioned and replicated using consistent hashing and consistency is facilitated by use of object versioning.

Cassandra

• Partitions data across the cluster using consistent hashing.

Spanner

• Provided data consistency and Supports SQL like Interface