NoSQL database acronyms

Last modified by Quentin Conner on 02/12/2014

Feb 12 2014

In my over-simplified view of the world, here is my summary of distributed database acronyms, in the order I remember their introduction.


What every web application has to do, repeatedly.

  • Create
  • Read
  • Update
  • Delete


  • Atomicity       (transaction context where operations all fail or all succeed)
  • Consistency  (data and relationships are valid -- think check constraint and foreign key constraint)
  • Isolation        (one client's uncommitted transaction invisible to others)
  • Durability       (committed writes survive power loss, other perils)

CAP (aka Brewer Theorem)

Choose two.

  • Consistency           (all nodes see same data at same time)
  • Availability              (every request gets a pass/fail response)
  • Partition tolerance  (loss of node)


  • Basically Available      (every request gets a pass/fail response)
  • Soft state                    (state may change without request arriving)
  • Eventual consistency  (system is async, stream-like.  it eventually becomes consistent after cessation of requests


  • helps solve the "last writer" problem due to "speed of light race condition"
  • forms consensus in network of unreliable processors (e.g. in presence of packet loss)
  • paxos is a consensus protocol, a state machine
  • proposer (asserts), acceptor (votes), learner (takes action upon consensus)
Created by Quentin Conner on 02/11/2014
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