Redis

Redis is an open source, BSD licensed, advanced key-value cache and store. When to redis when to mongodb

The Redis Interactive Tutorial is a great way to get started. Here some output I got while trying it out ...

Set the value foo vor the key k

>SET k "foo"
OK
>GET k
"foo"
[$[Get Code]]

You may use seperators in the keys, e.g.

>SET groupABC:user123:time001 "foo"
OK
[$[Get Code]]

Atomic value changes

>SET myCounter 42
OK
>INCR myCounter
(INTEGER) 43
>INCR myCounter
(INTEGER) 44
>DEL myCounter
(INTEGER) 1
>INCR myCounter
(INTEGER) 1
[$[Get Code]]

Autoexpire values

>SET resource:LOCK "Redis Demo"
OK
>EXPIRE resource:LOCK 120
(INTEGER) 1
>TTL resource:LOCK
(INTEGER) 115
>TTL resource:LOCK
(INTEGER) 106
[$[Get Code]]

Setting values resets its TTL

> SET resource:LOCK "Redis Demo 1"
OK
> EXPIRE resource:LOCK 120
(INTEGER) 1
> TTL resource:LOCK
(INTEGER) 119
> SET resource:LOCK "Redis Demo 2"
OK
> TTL resource:LOCK
(INTEGER) -1
[$[Get Code]]

List

>RPUSH friends "Alice"
(INTEGER) 1
>RPUSH friends "Bob"
(INTEGER) 2
>LPUSH friends "Sam"
(INTEGER) 3
>LRANGE friends 0 -1
1) "Sam"
2) "Alice"
3) "Bob"
>LRANGE friends 0 1
1) "Sam"
2) "Alice"
>LRANGE friends 1 2
1) "Alice"
2) "Bob"

>LLEN friends
(INTEGER) 3
>LPOP friends
"Sam"
>RPOP friends
"Bob"
>LLEN friends
(INTEGER) 1
>LRANGE friends 0 -1
1) "Alice"
[$[Get Code]]

Set, add, remove and test for element

> SADD superpowers "flight"
(INTEGER) 1
> SREM superpowers "reflexes"
0
> SISMEMBER superpowers "flight"
(INTEGER) 1
[$[Get Code]]

Sorted set, with value to sort with

> ZADD hackers 1940 "Alan Kay"
[$[Get Code]]

Hashes, more than one value for a key

> HSET USER:1000 name "John Smith"
(INTEGER) 1
> HSET USER:1000 email "john.smith@example.com"
(INTEGER) 1
> HSET USER:1000 password "s3cret"
(INTEGER) 1
> HGETALL USER:1000
1) "name"
2) "John Smith"
3) "email"
4) "john.smith@example.com"
5) "password"
6) "s3cret"
[$[Get Code]]

Increment value in Hash

> HSET USER:1000 visits 10
(INTEGER) 1
> HINCRBY USER:1000 visits 1
(INTEGER) 11
[$[Get Code]]