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.