Introduction to ElasticSearch

ElasticSearch

Presented by: Abuzar HasanArkhitech <http://www.arkhitech.com>

History

Shay Baron Compass in 2004 ElasticSearch in 2010

Written in Java Cross-platform Distributed

Users StumbleUpon

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Features Distributed and Highly Available Search Engine

Each index is fully sharded with a configurable number of shards Each shard can have one or more replicas Read / Search operations performed on either one of the replica

shard Multi Tenant with Multi Types Various set of APIs

Features Document Oriented

No need for upfront schema definition (Near) Real Time Search Per-Operation Persistence

Single document level operations are atomic, consistent, isolated and durable

Features Built on top of Lucene

Each shard is a fully functional Lucene index All the power of Lucene easily exposed through simple

configuration / plugins Independent of file format

Open Source under Apache 2 License

Setting Up Elastic Search Download ElasticSearch (CentOS)

sudo yum install elasticsearch

Start ElasticSearch Server elasticsearch -f -D

es.config=/usr/local/Cellar/elasticsearch/0.18.5/config/elasticsearch.yml

Setting up ElasticSearch w/ Ruby

The ElasticSearch is not ruby specific so 'tire' gem helps ruby based projects to communicate with ElasticSearch

'tire' gem https://github.com/karmi/retire

We then need to require following libraries require 'rubygems' require 'tire'

Indexing Records Indexing includes both “Create” and “Update” in CRUD. In order to make index request for new JSON object, we pass

the following URL http://localhost:<port>/<index>/<type>/[<id>].

Indexing Creating an index curl -XPUT "http://localhost:9200/movies/movie/1" -d'

{ "title": "The Godfather", "director": "Francis Ford Coppola", "year": 1972 }'

Indexing Response After executing the request, we get the following response

{ “ok”: true, “_index”: “movies”, “_type”: “movie”, “_id”: “1”, “_version”: 1

}

Retrieving Index Retrieving the index

curl -XGET "http://localhost:9200/movies/movie/1" -d''

Retrieve Index Response {

“_index”: “movies”, “_type”: “movie”, “_id”: “1”, “_version”: 1, “exists”: true, “_source”: {

"title": "The Godfather", "director": "Francis Ford Coppola", "year": 1972

} }

Delete Index Deleting the index

curl -XDELETE "http://localhost:9200/movies/movie/1" -d''

Demo Application Demo Application by karmi

$ rails new searchapp -m https://raw.github.com/karmi/tire/master/exam les/rails-application-template.rb

Demo: Search App - Model

Model include Tire::Model::Search include Tire::Model::Callbacks

These two 'tire' models allow your rails application to use tire gem for searching purposes

Demo: Search App - Controller

Controller @articles = Article.tire.search params[:query]

This line in your search method helps to search using tire gem

Demo: Search App - View View

<%= form_tag search_articles_path, method: :get do %> <%= text_field_tag :q, params[:query] %> <%= submit_tag :search %> <% end %>

Demo: Search App - Index Create an index

Tire.index 'articles' do delete create store :title => 'One', :tags => ['ruby'] store :title => 'Two', :tags => ['ruby', 'python'] store :title => 'Three', :tags => ['java'] store :title => 'Four', :tags => ['ruby', 'php'] refresh end

Demo: Search App - Index For custom mapping

Tire.index 'articles' do delete create :mappings => { :article => { :properties => { :id => { :type => 'string', :index => 'not_analyzed', :include_in_all => false }, :title => { :type => 'string', :boost => 2.0, :analyzer => 'snowball' }, :tags => { :type => 'string', :analyzer => 'keyword' }, :content => { :type => 'string', :analyzer => 'snowball' }

} } } end

Demo: Search App – Bulk Indexing

For indexing large amount of data articles = [

{ :id => '1', :type => 'article', :title => 'one', :tags => ['ruby'] }, { :id => '2', :type => 'article', :title => 'two', :tags => ['ruby', 'python'] }, { :id => '3', :type => 'article', :title => 'three', :tags => ['java'] }, { :id => '4', :type => 'article', :title => 'four', :tags => ['ruby', 'php'] }

] Use Import

Tire.index 'articles' do import articles end

Displaying Facets For displaying facets

s.results.facets['global-tags']['terms'].each do |f| puts "#{f['term'].ljust(10)} #{f['count']}"

end

Output ruby 3 python 1 php 1 java 1

QUESTIONS?

References• https://github.com/karmi/retire• http://railscasts.com/episodes/306-elasticsearch-part-

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