Redis
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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)).
![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](https://image.slidesharecdn.com/redis-140326170619-phpapp01/85/Redis-3-320.jpg)
Redis
- 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
Editor's Notes
- #2: Puneet Kumar
- #5: Strings $incr $incrby $setbit $getbitHashes hgetusers:gokupowerlevel $ hmsetusers:goku race saiyan age 737 $ hgetallusers:goku $ hkeysusers:goku $ hdelusers:goku age Lists $ltrimnewusers 0 49 Sets $sismemberfriends:letojessica $sinter friends:leto friends:duncan $sinterstorefriends:leto_duncanfriends:leto friends:duncanSorted Sets $zcount friends:duncan 90 100 $zrevrank friends:duncan chani