Database Reference
In-Depth Information
Key-Value stores
Key-Value stores are probably the simplest type of task-oriented NOSQL databases.
The data model of the original task at hand was probably not very complicated: Key-
Value stores are mostly based on a whitepaper published by Amazon at the biennial
ACM Symposium on Operating Systems Principles, called the Dynamo paper.
The data model discussed in that paper is that of Amazon's shopping cart system,
which was required to be always available and support extreme loads. Therefore,
the underlying data model of the Key-Value store family of database management
systems is indeed very simple: keys and values are aligned in an inherently schema-
less data model. And indeed, scalability is typically extremely high, with clustered
systems of thousands of commodity hardware machines existing at several high-end
implementations such as Amazon and many others. Examples of Key-Value stores
include the mentioned DynamoDB, Riak, Project Voldemort, Redis, and the newer
Aerospike. The following screenshot illustrates the difference in data models:
Key-Value Store
Database
Table: Customers
Table: Orders
ID: 1
ID: 252
First Name
: Andrew
Total Price
: 56432
: 300 USD
Last_Name
: Brust
Item 1
Street_Addr
: New York
: 123 Main St.
Item 2
: 98726
City
State
: 10014
: NY
ID: 265
Zip
Total Price
: 86413
: 2,500 EUR
Most recent_order
: 252
Item 1
Item 2
: 77904
ID: 2
First Name
: Napoleon
Last_Name
: Bonaparte
Street_Addr
: Paris
: 29, Rue de Rivoli
City
Postal Code
: France
: 75007
Counter
Most_recent_order
: 265
A simple Key-Value database
