Key-Value Stores

one of the most commonly used NoSQL paradigms today
- the key-value store bases its data model on the associative array data type
- thus getting a fast, flexible storage machine that resembles a hash table
Key-Value store is a flexible NoSQL database that's often used for caching and dynamic configuration
- is flexible because it does not impose structure
- is also simple because it is a key-value type of mapping
- is a type of database that allows you to store key-value pairs
  - mappings from keys which are typically strings to arbitrary values which are typically stored as strings
    - some key-value stores comes with specific typings, which allows you to store actual integers or actual arrays, etc
another way to think of key-value stores is as hash tables
using key-value stores is very fast and result in low latencies and increased throughput
although relational databases enables you to have powerful querying abilities
- its structure that is imposed on you can sometimes be more troublesome than useful
- during this case, using a non-relational database (NoSQL) might be better

Popular types

Amazon DynamoDB
ETCD
- is a strong consistent and highly available key-value store that's often used to implement leader election in a system
Redis
- an in memory key-value store
- does offer some persisten storage options but is typically used as a really fast, best-effort caching solution
- often used to implement rate limiting
Apache ZooKeeper
- is a strongly consistent, highly available key-value store
- often used to store important configuration or to perform leader election

sometimes you might want to have special parameters or constants in your system that different parts of the system can rely on
- best place to store these special parameters is in a key-value store