Redis NoSQL (Key-value) Database

Presenter: Mubashar Iqbal
Software Engineer

Classical variant - store data in a relational database:
• MySQL
• PostgreSQL
• H2
• SQLite and many more...
Modern trend in a Web programming:
• Store data in NoSQL databases
Databases

• Non-relational database management system
• Did not expose the standard SQL interface
• Does not conform to ACID
• Working with a huge quantity of data
• Does not require a relational model
• Distributed, fault-tolerant architecture
NoSQL Introduction

Categories of NoSQL Databases

Key-Value
Memcached, Redis, Riak

Column Family
Cassandra, HBase

Document
MongoDB, CouchDB

Graph
Neo4j, InfoGrid

Redis

Redis means Remote Dictionary Server

Open Source

Key-Value Data store

Data structure server

In-Memory Dataset

Written in ANSI C and Sponsored by Pivotal.
http://redis.io/topics/introduction

Why and when you should use Redis?

Caching

Master-slave replication, automatic failover

High-IO workloads

Distributed Locks

Data that expires

Cookie storage

Analytics

Ad Targeting

Search engines

Small Data

Bigger Data

Forums

Who is using Redis?
http://redis.io/topics/whos-using-redis

Storing lots of Pinterest lists in Redis
Next time you log in to Pinterest, remember that Redis is
running in the background and storing several types of lists for
you as a user:

A list of users who you follow

A list of boards (and their related users) who you follow

A list of your followers

A list of people who follow your boards

A list of boards you follow

A list of boards you unfollowed after following a user

The followers and unfollowers of each board

Installation
Linux:
1. $ wget http://download.redis.io/releases/redis-2.8.9.tar.gz
2. $ tar xzf redis-2.8.9.tar.gz
3. $ cd redis-2.8.9
4. $ make
5. $ sudo make install
6. $ cd utils
7. $ sudo ./install_server.sh
Windows:
1. Download the latest .exe package from
http://github.com/MSOpenTech/redis
2. Running the exe will install Redis as a service and install
the Redis client.

Configuration
Redis is able to start without a configuration file using a
built-in default configuration.
The proper way to configure Redis is by providing a Redis
configuration file, usually called redis.conf.

Port: 6379

Timeout: 300

Maxclients 10000

Maxmemory <bytes>

Save 900 1

Running Redis Server and Client
Once the script completes, the redis-server will be running
in the background.
You can start and stop redis with these commands.
sudo service redis_6379 start
sudo service redis_6379 stop
Access the redis database by typing the following
command.
redis-cli

Redis Clients

Phpredis – Redis client written in C for PHP.

Redis-py – Mature Redis client for Python.

Redis-rb – Very stable & Muture Client for Rubys

Scala-redis – Mature Redis client for Scala

Node_redis – Recommended client for node.

Jedis – Java client library for Redis.

Eredis – A Redis erlang client library.

Example Code
Write a simple php script to test redis php client:
<?php
$redis=new Redis() or die("Can't load redis client.");
$redis->connect('127.0.0.1', 6379);
$redis->set('set_testkey', 1);
?>
Parameters:
Host: string. can be a host, or the path to a unix domain socket
Port: int, optional
Return value:
BOOL: TRUE on success, FALSE on error.

Redis Data Types
Redis is often referred to as a data structure server since
keys can contain:

Strings

Lists

Sets

Hashes

Sorted Sets
http://redis.io/topics/data-types

Strings

Most basic kind of Redis value

Binary safe - can contain any kind of data

Max 512 Megabytes in length

Can be used as atomic counters using commands in the
INCR family
APPEND – Append a value to a key
GET – Get the value of a key
SET – Set the string value of a key
MGET – Get the values of all the given keys
MSET – Set multiple keys to multiple values

Lists

Lists of strings, sorted by insertion order

Add elements to a Redis List pushing new elements on the
head (on the left) or on the tail (on the right) of the list
LSET – Set the value of an element in a list by its index
LLEN – Get the length of a list
LREM – Remove elements from a list
LINSERT – Insert an element before or after another
element in a list
LRANGE – Get a range of elements from a list
LPOP – Remove and get the first element in a list
RPOP – Remove and get the last element in a list

Sets

Redis Sets are an unordered collection of Strings.

You can track unique things using Redis Sets.
SADD – Add one or more members to a set
SISMEMBER – Determine if a given value is a member of a set
SMEMBERS – Get all the members in a set
SPOP – Remove and return a random member from a set
SRANDMEMBER – Get one or multiple random members from a
set
SREM – Remove one or more members from a set

Hashes

Map between string fields and string values

Every hash can store more than 4 billion field-value pairs.
HSET – Set the string value of a hash field
HGET – Get the value of a hash field
HMGET – Get the values of all the given hash fields
HMSET – Set multiple hash fields to multiple values
HLEN – Get the number of fields in a hash
HKEYS – Get all the fields in a hash
HGETALL – Get all the fields and values in a hash

Sorted Sets

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

You can do a lot of tasks with great performance that are
really hard to model in other kind of databases

Probably the most advanced Redis data type
ZADD – Add one or more members to a sorted set, or update its
score if it already exists
ZREM – Remove one or more members from a sorted set
ZRANGE – Return a range of members in a sorted set, by index
ZINCRBY – Increment the score of a member in a sorted set

Replication
Master-slave replication that allows slave Redis servers to
be exact copies of master servers.

A master can have multiple slaves.

Slaves are able to accept connections from other slaves.

Replication can be used both for scalability and for data
redundancy.

Slave instance facility for scaling out read requests or
mitigate a disaster recovery scenario.

Setup the Master Server
To configure replication is very simple just add the following
line to the slave configuration file:
slaveof 192.168.1.1 6379
Replace 192.168.1.1 6379 with your master IP address and
port.
Replication only needs to be defined on Slave systems, the
Master server does not require any special configuration.

Performance
Popularity of Redis:

Speed

Rich semantics

Stability

Durability / Persistence
- Redis snapshots
- Append-only file (AOF)

Resources
1. http://www.redis.io
2. http://bencane.com/2013/11/12/installing-redis-
and-setting-up-master-slave-replication/
3. http://oldblog.antirez.com/post/redis-memcached-
benchmark.html
4. http://oldblog.antirez.com/post/update-on-
memcached-redis-benchmark.html
5. http://blog.gopivotal.com/pivotal/case-studies-
2/using-redis-at-pinterest-for-billions-of-relationships

Redis NoSQL (Key-value) Database

Redis NoSQL (Key-value) Database

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