Redis

What?

Open source in memory data structure store which can be used as a database and cache store.

Why?

Advantages of Redis

Flexible and no schema & column (NoSQL)
Performance (about 110, 000 SETs per second, about 81, 000 GETs per second)
Rich datatype support
Cache & Disk persistence

What Redis is not good at..

Data encryption is not supported

What is usage?

Real time analytics
High speed data ingest
Session storage
Application job manage
Message queus
Geo search
Cache!

Data Types

String
Lists
Sets
Stored Sets
Hashes
Bitmaps
Hyperlogs
Geospatial indices

GET (node.js)

client.get("missingkey", function(err, reply) {
    // reply is null when the key is missing
    console.log(reply);
});

SET (node.js)

client.set('key', 'value!', 'EX', 10);

INCR

INCR foo // 100
101

DECR

DECR foo // 100
99

EXISTS

EXISTS foo 
// 1 if it is set

DEL

DEL foo
// => 1
EXISTS foo 
// 0

FLUSHALL

FLUSHALL
0

EXPIRE

EXPIRE foo 50
// 1

TTL

TTL foo

SETEX

SETEX foo 50 "hello"

PERSIST

Make key persist

PERSIST foo
TTL foo
// -1

MSET

Set more than 1 pairs.

MSET foo "hello" bar "world"

APPEND

Append value to the value corresponding to key.

APPEND foo " world"

GET foo "hello world"

RENAME

RENAME foo foo1

List Commands

LPUSH

LPUSH people "John"
LPUSH people "Tom"

LRANGE

LRANGE allows you to pull data on the range of 0 to -1 (-1 is last index)

LRANGE people 0 -1
1) John
2) Tom

LLEN

LLEN gives length of key

LLEN people

LPOP

LPOP pops element.

LPOP people
// "Tom"

LINSERT

Insert value to key

LINSERT people BEFORE "Brad" "Jen"

Options

EX seconds -- Set the specified expire time, in seconds.

PX milliseconds -- Set the specified expire time, in milliseconds.

NX -- Only set the key if it does not already exist.

XX -- Only set the key if it already exist.

Why Redis?

Using Redis as an LRU cache

Dave Nielsen: Top 5 uses of Redis as a Database

Scaling Redis at Twitter

Redis Crash Course Tutorial

Build A Node.js & Redis App From Scratch

In Memory Database