NoSQL

Key-Value Stores

• Interface: extremely simple
  1. Data model: (key, value) pairs
  2. Operations: Insert(key, value), Fetch(key), Update(key), Delete(key)
  3. Some allow (non-uniform) columns within value.
  4. Some allow Fetch on range of keys.

• Implementation: efficiency, scalability, fault-tolerance
  • Records distributed to nodes based on key
  • Replication
  • Single-record transactions, "eventual consistency".