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Introduction and side by side comparison of Redis and MongoDB
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Introduction into Mongo and Redis
the basics for people who are used to AR
What are they for?
● MongoDB:● Document oriented
database● Queries can be written
in Javascript● Scalable and flexible● Typical usecase:
Databases that are rather schema-free
● Redis● Key Value Store● Own Jquery-similar
selectors● Scalable and flexible● Typical usecase:
Logging, Queues and other denormalized things
Schema - Free
● Schema – Free means, that you don't want to denormalize your data.
● It is especially useful, when you wan't to leave it to the user or the situation, what fields you want to store exactly
● You can also use 'schema free sql', which means, you can work around the schema in sql databases
● But here we refer to what is called 'NOSQL'
Persistence
● Mongo-DB:● Mongo is being
persited automatically
● Redis:● Redis has two modes
of persistence:– Snapshotting:
● In certain intervals or manually you write a copy of everything in memory on the hard disk
– Append Only Log● new information is
appended to the logfile on disk
Usage in Ruby / Rails
● Mongo DB:● Mongoid or
Mongomapper as replacement for ActiveRecord
● Redis:● Redis – Gem
Mongo Example
# with Mongomapper
class Story include MongoMapper::Document key :title, String key :url, String key :slug, String key :voters, Array key :votes, Integer, :default => 0 key :relevance, Integer, :default => 0 # Cached values. key :comment_count, Integer, :default => 0 key :username, String # Note this: ids are of class ObjectId. key :user_id, ObjectId timestamps! # Relationships. belongs_to :user # Validations. validates_presence_of :title, :url, :user_idend
# To find all the stories voted on by a given user:
Story.all(:conditions => {:voters => @user.id})
Mongo with Mongoid
class Artist include Mongoid::Document field :name, type: String embeds_many :instrumentsendclass Instrument include Mongoid::Document field :name, type: String embedded_in :artistend# Find the first artist named "Syd Vicious" and create an embedded bass# document for him. Of course he'll smash it within the next few minutes,# but no worries we can delete it later.Artist.where(name: "Syd Vicious").first.tap do |artist| artist.instruments.create(name: "Bass")end
concept of embedded documents
QUERY METHODS
Model.all_in
Model.all_of
Model.also_in
Criteria#and
Model.any_in
Model.any_of
Model.asc
Model.desc
Criteria#distinct
Model.excludes
Model.includes
Model.limit
Model.near
Model.not_in
Model.only
Model.order_by
Model.skip
Model.where
Model.without
Mongo Query Selectors
● db.COLLECTION.find()
● db.users.find({“age” : 23})
● default is AND
● SELECT: db.users.find({},{“username” : 1})
● $gte, $lte, $gt, $lt, $ne : comparisons
● db.users.find({“age” : {“$gte” : 18 }})
● OR:
● using $in: db.users.find({“user_id” {“$in” : [“1”,”2”]}})
● db.users.find({“$or” : [{“name” : “foo”},{“title” : “bar”}]})
● others:
● $not, $all, $any, $size, $slice
● regular expression: {“name” : /foo?/i}
● in embedded documents:
● db.users.find({“name.first” : “Foo”, “name.last” : “Bar”})
● use javascript with $where
● db.foo.find({“$where” : “this.x + this.y == 10”})
● db.fo.find({“$where” : “function() {return this.x + this.y == 10;}”})
collection ~= 'table'
>=, <=, >, <
nesting with a 'dot'
Redis Example
$redis = Redis.new(:host => 'localhost', :port => 6379)
$redis
=> #<Redis client v2.1.1 connected to redis://localhost:6379/0 (Redis v2.2.2)>
$redis.set('chunky', 'bacon')
=> "OK"
$redis.get('chunky')
=> "bacon"
Redis Lists
● Lists● RPUSH: push to the right● LPUSH: push to the left● LPOP: pops from the left● RPOP: pops from the right● BLOP: blocking left pop● BRPOP: blocking right pop
KEY Operations
● SET● GET● INCR: increments the value● INCRBY: increments the value by● DECR: decrements the value● DECRBY: decrements the value by● KEYS (pattern) : display all keys matching pattern● TYPE : gives us the type of a key
Redis Example: Queuing
def enqueue(queue_name, data) $redis.sadd(“queues”, queue_name) $redis.rpush(“queue:#{queue_name}”, data.to_json)end
def deque(queue_name) $redis.blpop(“queue:#{queue_name}”,60) # pops and WAITSend
def work(queue_name) while true do job = self.dequeue(queues) proces_job(job) if job endend
1
Introduction into Mongo and Redis
the basics for people who are used to AR
2
What are they for?
● MongoDB:● Document oriented
database● Queries can be written
in Javascript● Scalable and flexible● Typical usecase:
Databases that are rather schema-free
● Redis● Key Value Store● Own Jquery-similar
selectors● Scalable and flexible● Typical usecase:
Logging, Queues and other denormalized things
3
Schema - Free
● Schema – Free means, that you don't want to denormalize your data.
● It is especially useful, when you wan't to leave it to the user or the situation, what fields you want to store exactly
● You can also use 'schema free sql', which means, you can work around the schema in sql databases
● But here we refer to what is called 'NOSQL'
4
Persistence
● Mongo-DB:● Mongo is being
persited automatically
● Redis:● Redis has two modes
of persistence:– Snapshotting:
● In certain intervals or manually you write a copy of everything in memory on the hard disk
– Append Only Log● new information is
appended to the logfile on disk
5
Usage in Ruby / Rails
● Mongo DB:● Mongoid or
Mongomapper as replacement for ActiveRecord
● Redis:● Redis – Gem
6
Mongo Example
# with Mongomapper
class Story include MongoMapper::Document key :title, String key :url, String key :slug, String key :voters, Array key :votes, Integer, :default => 0 key :relevance, Integer, :default => 0 # Cached values. key :comment_count, Integer, :default => 0 key :username, String # Note this: ids are of class ObjectId. key :user_id, ObjectId timestamps! # Relationships. belongs_to :user # Validations. validates_presence_of :title, :url, :user_idend
# To find all the stories voted on by a given user:
Story.all(:conditions => {:voters => @user.id})
7
Mongo with Mongoid
class Artist include Mongoid::Document field :name, type: String embeds_many :instrumentsendclass Instrument include Mongoid::Document field :name, type: String embedded_in :artistend# Find the first artist named "Syd Vicious" and create an embedded bass# document for him. Of course he'll smash it within the next few minutes,# but no worries we can delete it later.Artist.where(name: "Syd Vicious").first.tap do |artist| artist.instruments.create(name: "Bass")end
concept of embedded documents
QUERY METHODS
Model.all_in
Model.all_of
Model.also_in
Criteria#and
Model.any_in
Model.any_of
Model.asc
Model.desc
Criteria#distinct
Model.excludes
Model.includes
Model.limit
Model.near
Model.not_in
Model.only
Model.order_by
Model.skip
Model.where
Model.without
8
Mongo Query Selectors
● db.COLLECTION.find()
● db.users.find({“age” : 23})
● default is AND
● SELECT: db.users.find({},{“username” : 1})
● $gte, $lte, $gt, $lt, $ne : comparisons
● db.users.find({“age” : {“$gte” : 18 }})
● OR:
● using $in: db.users.find({“user_id” {“$in” : [“1”,”2”]}})
● db.users.find({“$or” : [{“name” : “foo”},{“title” : “bar”}]})
● others:
● $not, $all, $any, $size, $slice
● regular expression: {“name” : /foo?/i}
● in embedded documents:
● db.users.find({“name.first” : “Foo”, “name.last” : “Bar”})
● use javascript with $where
● db.foo.find({“$where” : “this.x + this.y == 10”})
● db.fo.find({“$where” : “function() {return this.x + this.y == 10;}”})
collection ~= 'table'
>=, <=, >, <
nesting with a 'dot'
9
Redis Example
$redis = Redis.new(:host => 'localhost', :port => 6379)
$redis
=> #<Redis client v2.1.1 connected to redis://localhost:6379/0 (Redis v2.2.2)>
$redis.set('chunky', 'bacon')
=> "OK"
$redis.get('chunky')
=> "bacon"
10
Redis Lists
● Lists● RPUSH: push to the right● LPUSH: push to the left● LPOP: pops from the left● RPOP: pops from the right● BLOP: blocking left pop● BRPOP: blocking right pop
11
KEY Operations
● SET● GET● INCR: increments the value● INCRBY: increments the value by● DECR: decrements the value● DECRBY: decrements the value by● KEYS (pattern) : display all keys matching pattern● TYPE : gives us the type of a key
12
Redis Example: Queuing
def enqueue(queue_name, data) $redis.sadd(“queues”, queue_name) $redis.rpush(“queue:#{queue_name}”, data.to_json)end
def deque(queue_name) $redis.blpop(“queue:#{queue_name}”,60) # pops and WAITSend
def work(queue_name) while true do job = self.dequeue(queues) proces_job(job) if job endend
