Basic Introduction of Redis

1. An Introduction to
By: Tanu Siwag &
Deepak Kr Mittal

2. Agenda
Overview
Redis Advantages
Comparision with other key-value storage
Environment Setup - Install Redis
Redis - Data Types : Strings, Hashes, Lists, Sets, Sorted Sets
Redis Keys and Key Commands

3. Agenda (Cont...)

Pub-Sub

Transactions

Redis - Connections

Redis – Backup

Redis – Security

Benchmark

4. What is Redis?

REmote DIctionary Server (Data Structure server)

Redis is an open source, advanced key-value store

Written in c

Solution for building high-performance, scalable web
applications.

In-memory storage,with persistence.

Rich set of data types

Redis can replicate data to any number of slaves.

5. Who all are using Redis?

6. Why Redis?

Simple to learn

Lightweight text-based tcp protocol

Extremely fast and versatile - in RAM

Rapidly growing

Widely supported (C, .NET, PHP, Java... more)

Disk-backed, Background writes!

Master-Slave configurations

Open source , awesome community

7. Advantages of Redis

Exceptionally Fast (110000 SETs per second, 81000 GETs per
second)

Supports Rich data types

Snapshots

Atomic Operations

Replication

Sharding

MultiUtility Tool (caching, messaging-queues, any short lived data
in application like web application sessions, web page hit counts,
etc)

8. Comparision with other key-value stores

Complex data types, with atomic operations

Redis is an in-memory but persistent on disk database

very high write and read speed

Memory representation of complex data structures is much
simpler

Little internal complexity.

9. Memcache Vs Redis
Memcached Redis
Description In-memory key-value store,
originally intended for caching
In-memory database with
configurable options performance
vs. persistency
Initial
release
2003 2009
Transaction
concepts
none optimistic locking
Partitioning
methods
none Sharding
Durability no yes
Replication
methods
none Master-slave replication

10. Memcache Vs Redis
Memcached Redis
Memory
Usage
For simple key-value pairs
memcached is more memory
efficient than Redis
If use Redis hashes, then Redis is
more memory efficient.
Persistence Data lost with a restart &
rebuilding cache is a costly
process
Persistent data. Redis syncs to disk
at every 2 seconds.
Storage
Type
Stores variables in
memory
Database that resides in
memory
Read/ Write
Speed
Heavy Read Heavy Read & Write
Key Length 250 bytes max 2 GB max
Data
Structure
String & integer
Object: serialize
stronger data structures

11. Install Redis on Ubuntu

$sudo apt-get install redis-server

Check if redis is working?
$redis-cli

Run commands on remote server
redis-cli -h host -p port -a password

12. Install Redis on Ubuntu

$ wget http://redis.googlecode.com/files/redis-2.4.2.tar.gz

$ tar xzf redis-2.4.2.tar.gz

$ cd redis-2.4.2

$ make

Start Redis: redis-server

13. Install Redis Desktop Manager on Ubuntu

Will provide UI to manage your redis keys and data.

Download from : http://redisdesktop.com/download

Install the downloaded file

14. Ping – Pong Game
Install Redis on your systems

15. Redis Key Commands

SET

GET

DEL

DUMP (serialized version)

EXISTS

EXPIRE key seconds

EXPIREAT key timestamp

PEXPIRE key milliseconds

16. Redis Key Commands (Cont..)

PEXPIREAT key milliseconds-timestamp

KEYS pattern

MOVE key db (move key to another db)

PERSIST (Remove expiration)

TTL (Remaining time in key expiry)

PTTL (Remaining time in key expiry in milliseconds)

RANDOMKEY

RENAME key newkey (RENAMENX)

TYPE key

17. Key => { Data Structures }
KEYKEY
““I am a plain text string”I am a plain text string”
C A A B DC A A B D
A B C D EA B C D E
A : 0.1 B : 0.2 C : 50 D : 50A : 0.1 B : 0.2 C : 50 D : 50
KEY 1KEY 1
KEY 2KEY 2
Value 1Value 1
Value 2Value 2
Hash Tables
(objects)
Strings/Bitmaps
Lists
Sets
Sorted Sets
String

18. Redis Data Types

Strings

Hashes

Lists

Sets

Sorted Sets

19. Redis – String

For managing Strings values

Sequence of bytes

Binary safe

Max 512 Megabytes in length

20. Redis – String
Redis Key
Value: Redis String
String (512 MB max)

21. Redis – String Commands

GET/SET

GETRANGE key start end

GETSET key value

MGET key1 key2 / MSET key1 val1 key2 val2

SETEX key seconds value / PSETEX

SETNX key value / MSETNX

SETRANGE key offset value

STRLEN key

22. Redis – String Commands (Cont..)

EXISTS key

DEL key

INCR key / DECR

INCRBY key inc / DECRBY

INCRBYFLOAT key inc

APPEND key value

23. Redis – Hashes

Collection of key value pair

Maps b/w string fields and string values

Used to represent objects

Can store upto more thn 4 billion field-value pairs

24. Redis – Hashes
Redis Key
Field1
Field3 Value3
Value2
Value1
Field2
Value : Redis Hash

25. Redis – Hashes Commands

HSET key field val /HMSET

HGET key field /HMGET key field1 field2

HGETALL key

HDEL key field1 field2

HEXISTS key field

HINCRBY key field inc / HINCRBYFLOAT

HKEYS key

HLEN key

HSETNX key field value

HVALS key

HSCAN

26. Redis – Hashes Example
redis 127.0.0.1:6379> HMSET session name "Intro to redis" description "redis basic
commands for caching" attendees 20 absent 5
OK
redis 127.0.0.1:6379> HGETALL session
1) "name"
2) "Intro to redis"
3) "description"
4) "redis basic commands for caching"
5) "attendees"
6) "20"
7) "absent"
8) "5"

27. Redis – Lists

List of strings, sorted by insertion order

Can add elements on head or on tail

Maximum length of a list is 232 - 1 elements (4294967295, more than
4 billion of elements per list)

28. Redis – Lists
Redis Key
HEAD
Value2
Value4 TAIL
Value3
Value1
Value : Redis List

29. Redis – Lists Commands

LPOP key / LPUSH key value1 [value2]

RPOP key / RPUSH key value1 [value2]

BLPOP key1 [key2 ] timeout

BRPOP key1 [key2 ] timeout

BRPOPLPUSH source destination timeout

LINDEX key index

LINSERT key BEFORE|AFTER pivot value

LLEN key

30. Redis – Lists Commands (Cont..)

LPUSHX key value

LRANGE key start stop

LREM key count value

LSET key index value

LTRIM key start stop

RPOP key / RPUSH key value1 [value2]

RPOPLPUSH source destination

RPUSHX key value

31. Redis – Lists Example
redis 127.0.0.1:6379> lpush sessionList redis
(integer) 1
redis 127.0.0.1:6379> lpush sessionList mongodb
(integer) 2
redis 127.0.0.1:6379> lpush sessionList rabitmq
(integer) 3
redis 127.0.0.1:6379> lrange sessionList 0 10
1) "rabitmq"
2) "mongodb"
3) "redis"

32. Redis – Sets

Unordered collection of unique strings

Can add, remove and test for existence

Diff, intersect, merge

Maximum length of a list is 232 - 1 elements (4294967295, more than
4 billion of elements per set)

33. Redis – Sets
Redis Key
Value2 Value4
Value3
Value1
Value : Redis Set

34. Redis – Sets Commands

SADD key member1 [member2] / SPOP key

SREM key member1 [member2]

SCARD key

SDIFF key1 [key2]

SDIFFSTORE destination key1 [key2]

SINTER key1 [KEY2]

SINTERSTORE destination key1 [key2]

SUNION key1 [key2]

SUNIONSTORE destination key1 [key2]

35. Redis – Sets Commands (Cont..)

SISMEMBER key member

SMEMBERS key

SRANDMEMBER key [count]

SMOVE source destination member

SSCAN key cursor [MATCH pattern]

36. Redis – Sets Example
redis 127.0.0.1:6379> SADD sessionSet redis
(integer) 1
redis 127.0.0.1:6379> SADD sessionSet mongodb
(integer) 1
redis 127.0.0.1:6379> SADD sessionSet rabitmq
(integer) 1
redis 127.0.0.1:6379> SADD sessionSet rabitmq
(integer) 0
redis 127.0.0.1:6379> SMEMBERS sessionSet
1) "rabitmq"
2) "mongodb"
3) "redis"

37. Redis – Sorted Sets

Similar to Set

Every member of a Sorted Set is associated with score, that is used in
order to take the sorted set ordered, from the smallest to the
greatest score.

Ordered by score

Members are unique, scores may be repeated.

Can add, remove and test for existence

Maximum length of a list is 232 - 1 elements (4294967295, more than
4 billion of elements per set)

38. Redis – Sorted Sets
Redis Key
Score 100
Value2
Score 300
Value1
Score 300
Value4
Score 50
Value3
Value : Redis Sorted Set

39. Redis – Sorted Sets Commands

ZADD key score1 member1 [score2 member2]

ZCARD key

ZCOUNT key min max

ZINCRBY key increment member

ZINTERSTORE destination numkeys key [key ...]

ZRANGE key start stop WITHSCORES
ZRANGEBYSCORE key min max [WITHSCORES] [LIMIT]

ZRANK key member

40. Redis – Sorted Sets Commands (Cont..)

ZREM key member [member ...]

ZREMRANGEBYRANK key start stop

ZREMRANGEBYSCORE key min max

ZREVRANGE key start stop [WITHSCORES]

ZREVRANGEBYSCORE key max min [WITHSCORES]

ZREVRANK key member

ZSCORE key member

ZUNIONSTORE destination numkeys key [key ...]

ZSCAN key cursor [MATCH pattern]

41. Redis – Sorted Sets Example
redis 127.0.0.1:6379> ZADD sessionscore 1 redis
(integer) 1
redis 127.0.0.1:6379> ZADD sessionscore 2 mongodb
(integer) 1
redis 127.0.0.1:6379> ZADD sessionscore 3 rabitmq
(integer) 1
redis 127.0.0.1:6379> ZADD sessionscore 4 rabitmq
(integer) 0
redis 127.0.0.1:6379> ZRANGE sessionscore 0 10 WITHSCORE
1) "redis"
2) “1”
3) "mongodb"

42. Redis – Publish Subscribe

Messaging system

The link by which messages are transferred is called channel

A client can subscribe any number of channels.

redis 127.0.0.1:6379> SUBSCRIBE redisChat

redis 127.0.0.1:6379> PUBLISH redisChat "Redis is a great caching
technique"

43. Redis – Pub Sub Commands

PUBLISH channel message

SUBSCRIBE channel [channel...]

PSUBSCRIBE pattern [pattern2...]

PUBSUB subcommand [argument [argument]]

UNSUBSCRIBE [channel [channel...]]

PUNSUBSCRIBE [pattern [pattern...]]

44. Redis – Transactions

Allow the execution of a group of commands in a single step

Two properties:
− All commands are serialized and executed sequentially
− Either all commands or no commands are processed

Iinitiated by command MULTI

Executed by EXEC command

45. Redis – Transactions Commands

DISCARD

EXEC

MULTI

UNWATCH

WATCH key [key...]

46. Redis – Connections

To manage client connections with redis server

47. Redis – Connection Commands

AUTH password

ECHO message

PING

QUIT

SELECT index

48. Redis Configuration

Redis.conf available at root directory of redis.

CONFIG GET *

CONFIG SET CONFIG_SETTING_NAME NEW_CONFIG_VALUE

49. Redis – Security

Redis database can be make secured

Making connection needs to authenticate before executing
command.

127.0.0.1:6379> CONFIG get requirepass

50. Redis – Security Commands
127.0.0.1:6379> CONFIG set requirepass "intellimeet"
127.0.0.1:6379> CONFIG get requirepass
1) "requirepass"
2) "intellimeet"
NOAUTH Authentication required error
Client needs to use AUTH command to authenticate himself.
127.0.0.1:6379> AUTH "intellimeet"
127.0.0.1:6379> SET mykey "Test value"
127.0.0.1:6379> GET mykey
"Test value"

51. Redis – Backup

SAVE command is used to create back up of current redis database

This command will create dump.rdb file in your redis directory.

To restore redis data just move redis backup file (dump.rdb) into your
redis directory and start the server.

CONFIG get dir : to get redis directory

52. Redis – Backup (Cont..)

BGSAVE start the backup process and run in background

Default configuration:
− Save after 900 sec (15 min) if at least 1 key changed
− Save after 300 sec (5 min) if at least 10 keys changed
− Save after 60 sec if at least 10000 keys changed

53. Redis – Some other useful Commands

DBSIZE

SELECT

FLUSHALL

FLUSHDB

INFO

LASTSAVE (Last unsuccessful save)

MONITOR

SHUTDOWN

SLAVEOF

54. Redis – Benchmarks

Utility to check the performance of redis

Running n commands simultaneously

redis-benchmark [option] [option value]

redis-benchmark -n 100000

redis-benchmark -h 127.0.0.1 -p 6379 -t set,lpush -n 100000 -q

SET: 146198.83 requests per second

LPUSH: 145560.41 requests per second

55. Why not Redis?

Single Threaded

Significant overhead for persistence

Pick your risk level Vs performance
If your db is too big - redis can handle swapping on its own.
Keys remain in memory and least used values are swapped to
disk.
Swapping IO happens in separate threads
But if you need this - don't use redis, or get a bigger machine ;)

56. Redis Commands Link

http://redis.io/commands

Try Redis- in real time
− http://try.redis-db.com

57. Other use case ideas

Geo Resolving with geohashing
− Implemented and opened by yours truly
https://github.com/doat/geodis

Real time analytics
− use ZSET, SORT, INCR of values

API Key and rate management
− Very fast key lookup, rate control counters using INCR

Real time game data
− ZSETs for high scores, HASHES for online users, etc

Database Shard Index
− map key => database id. Count size with SETS