"Most of these services only store and retrieve data by primary key
and do not require the complex querying and management functionality
offered by an RDBMS. This excess functionality requires expensive
hardware and highly skilled personnel for its operation, making it a
very inefficient solution. In addition, the available replication
technologies are limited and typically choose consistency over
1) Most web work is primary key.
2) Its not transactional.
3) Availability is more important then a lost data