Data Systems : combines different data storage technologies : caches, indexes and data in sync with application code : API(application programming interface) to hide architectural complexity : There are three ways to deal with requests in this figure, 1. In-memory cache 2. Primary database 3. Full-text index Before checking DB, check the cache to see if the data is cached. If there is no cache, ..

NoSQL (Not only SQL, Non-SQL) Categories of NoSQL Systems Key-Value based NoSQL: Riak, Redis, Scalaris, Amazon DynamoDB Document-based NoSQL: MongoDB, CouchDB, OrientDB Column-base NoSQL: Google BigTable, Cassandra, Hbase, Amazon DynamoDB, Graph-based NoSQL: Neo4J, InfoGrid, FlockDB ACID Principle: RDBMS Gold Standard! Atomicity: Transactions are completely done or not done at all. Consistency: ..