Redis is an in-memory data structure store that can be used as a database, cache, and message broker. It supports strings, hashes, lists, sets, sorted sets with operations like gets, sets, incr, and exploring data structures. Redis also supports transactions, pub/sub, LRU caching, and replication. Common commands provide basic CRUD operations and data structure operations with time complexities from O(1) to O(N+M*log(M)).

1. Redis
Installing
Basics
Data structures
Pseudo Multi Key Queries
References and Indexes
Round Trips and Pipelining
Transactions
Keys Anti pattern, Use SCAN
Expire, Pub-Sub
Monitor, Sort
Administration
A few commands
Big O
Reference

2. iNSTALLING
• Download redis-2.8.7.tar.gz, untar
• $ make $ make test $ cd src
• $ redis-server #server accepts connections on port6379
• $ redis-cli
• $$ info
• $ redis-benchmark

3. basics
• In-memory persistent key-value store 5 data structures
• $select 1 # many databases
• $ set users:leto '{"name": "leto", "planet": "dune", "likes": ["spice"]}’ #
Every data struct has key eg users:leto
• $ get users:leto # Values are arbitrary byte arrays that Redis doesn’t
care about

4. Data Structures
• Strings $strlen $getrange $append
• Hashes $hset users:goku powerlevel 9000
• Lists $ lpush newusers goku
• Sets $sadd friends:leto ghanima paul chani jessica
• Sortd Sets $ zadd friends:duncan 70 ghanima 95 paul 95 chani 75
jessica 1 vladimir

5. Pseudo Multi Key Queries
• $set users:9001 '{"id": 9001, "email": "leto@dune.gov", ...}’
• $hset users:lookup:email leto@dune.gov 9001
• $get users:9001
• $id = redis.hget('users:lookup:email' , 'leto@dune.gov' ) # ruby
• $user = redis.get("users:#{id}" ) # ruby

6. References and Indexes
• $sadd friends:leto ghanima paul chani jessica
• $sadd friends_of:chani leto paul
• # having to manually deal with references in Redis is
unfortunate.

7. Round Trips and Pipelining
• #Redis also supports pipelining. Normally when a
client sends a request to Redis it waits for the reply
before sending the next request. With pipelining you
can send a number of requests without waiting for
their responses.

8. Transactions
• $multi
• $hincrby groups:1percent balance -9000000000
• $hincrby groups:99percent balance 9000000000
• $exec # Or use command discard
• $ redis.watch('powerlevel' ) #ruby
• $ current = redis.get('powerlevel' ) #ruby
• $ redis.multi() #ruby
• $ redis.set('powerlevel' , current + 1) #ruby
• $ redis.exec() #ruby

9. Keys Anti pattern, Use
SCAN
• $ keys bug:1233:*
• #command takes a pattern and finds all the matching keys
• #Should never be used in production code. Linear scan through all the
keys.
• Better:
• $hset bugs:1233 1 '{"id":1, "account": 1233, "subject": "..."}’
• $hset bugs:1233 2 '{"id":2, "account": 1233, "subject": "..."}’
• $ scan 0 match bugs:* count 20 $ hscan $sscan $zscan

10. Expire, Pub-Sub
• $expire pages:about 30
• $ ttl pages:about
• $ persist pages:about
• $ setex pages:about 30 '<h1>about us</h1>....’
• $ subscribe warnings $unsubscribe $punsubscribe
• $ publish warnings "it's over 9000!” $psubscribe warnings:*)
• $blpop $brpop

11. Monitor, Sort
• $ monitor
• $ config set slowlog-log-slower-than 0
• $ slowlog $ slowlog len
• $ sort users:leto:guesses
• $ sort friends:ghanima limit 0 3 desc alpha
• $ sort watch:leto by severity:* desc
• $ sort watch:leto by bug:*->priority get bug:*->details
• $ sort watch:leto by bug:*->priority get bug:*->details store
watch_by_priority:leto

12. Administration
• $ config get *log* # http://download.redis.io/redis-stable/redis.conf
• $ requirepass $ auth password
• $ rename-command FLUSHALL
1041285018a942a4922cbf76623b741e
• $ slaveof # Replication

13. A few commands
• Auth, echo, ping, quit, select
• Del, dump, exists, expire, expireat, keys, migrate, move, object, persi
st, pexpire, pexpireat, pttl, randomkey, rename, renamenx, restore, so
rt, ttl, type, scan
• Append, bitcount, bitop, bitops, decr, decrby, get, getbit, getrange, get
set, inc, incrby, incrbyfloat, mget, mset, msetnx, psetex, set, setbit, set
ex, setnx, setrange, strlen

14. Big O
• O(1) sismember
• O(log(N) zadd ltrim
• O(log(N)+M) zremrangebyscore
• O(N+M*log(M)) sort
• O(Nˆ2) and O(CˆN) no commands

15. reference
• http://github.com/karlseguin/the-little-redis-book