Terminology
===========

redundancy

durability

Consistency

vertical scaling or scaling up

horizontally, or scaling out (MongoDB scales horizontally by partitioning data in a processes known as sharding.)

accumulating

granular

fault tolerance

compound indexes (As a general rule, a query where one term demands an exact match and another specifies a range requires a compound index where the range key comes second.)

pages (4 KB chunks called pages)

In MongoDB’s B-tree implementation, a new node is allocated 8,192 bytes(8KB)

The maximum key size in MongoDB v2.0 is 1024 bytes

page fault 

thrashing

ubiquitous btree (http://www.cl.cam.ac.uk/~smh22/docs/ubiquitous_btree.pdf)

sparse != dense

covering indexes = index-only queries

concern

high cardinality

Replication

network latency

arbiter

ACID (Atomicity, Consistency, Isolation, Durability)