Tire is a Ruby (1.8 or 1.9) client for the ElasticSearch search engine/database.
ElasticSearch is a scalable, distributed, cloud-ready, highly-available, full-text search engine and database with powerfull aggregation features, communicating by JSON over RESTful HTTP, based on Lucene, written in Java.
This Readme provides a brief overview of Tire's features. The more detailed documentation is at http://karmi.github.com/tire/.
Both of these documents contain a lot of information. Please set aside some time to read them thoroughly, before you blindly dive into „somehow making it work“. Just skimming through it won't work for you. For more information, please refer to the integration test suite and issues.
OK. First, you need a running ElasticSearch server. Thankfully, it's easy. Let's define easy:
$ curl -k -L -o elasticsearch-0.17.6.tar.gz http://github.com/downloads/elasticsearch/elasticsearch/elasticsearch-0.17.6.tar.gz
$ tar -zxvf elasticsearch-0.17.6.tar.gz
$ ./elasticsearch-0.17.6/bin/elasticsearch -f
See, easy. On a Mac, you can also use Homebrew:
$ brew install elasticsearch
Now, let's install the gem via Rubygems:
$ gem install tire
Of course, you can install it from the source as well:
$ git clone git://github.com/karmi/tire.git
$ cd tire
$ rake install
Tire exposes easy-to-use domain specific language for fluent communication with ElasticSearch.
It easily blends with your ActiveModel/ActiveRecord classes for convenient usage in Rails applications.
To test-drive the core ElasticSearch functionality, let's require the gem:
require 'rubygems'
require 'tire'Please note that you can copy these snippets from the much more extensive and heavily annotated file in examples/tire-dsl.rb.
Also, note that we're doing some heavy JSON lifting here. Tire uses the multi_json gem as a generic JSON wrapper, which allows you to use your preferred JSON library. We'll use the yajl-ruby gem in the full on mode here:
require 'yajl/json_gem'Let's create an index named articles and store/index some documents:
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
endWe can also create the index with custom mapping for a specific document type:
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' }
}
}
}
endOf course, we may have large amounts of data, and it may be impossible or impractical to add them to the index
one by one. We can use ElasticSearch's
bulk storage.
Notice, that collection items must have an id property or method,
and should have a type property, if you've set any specific mapping for the index.
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'] }
]
Tire.index 'articles' do
import articles
endWe can easily manipulate the documents before storing them in the index, by passing a block to the
import method, like this:
Tire.index 'articles' do
import articles do |documents|
documents.each { |document| document[:title].capitalize! }
end
refresh
endIf this declarative notation does not fit well in your context, you can use Tire's classes directly, in a more imperative manner:
index = Tire::Index.new('oldskool')
index.delete
index.create
index.store :title => "Let's do it the old way!"
index.refreshOK. Now, let's go search all the data.
We will be searching for articles whose title begins with letter “T”, sorted by title in descending order,
filtering them for ones tagged “ruby”, and also retrieving some facets
from the database:
s = Tire.search 'articles' do
query do
string 'title:T*'
end
filter :terms, :tags => ['ruby']
sort { by :title, 'desc' }
facet 'global-tags' do
terms :tags, :global => true
end
facet 'current-tags' do
terms :tags
end
end(Of course, we may also page the results with from and size query options, retrieve only specific fields
or highlight content matching our query, etc.)
Let's display the results:
s.results.each do |document|
puts "* #{ document.title } [tags: #{document.tags.join(', ')}]"
end
# * Two [tags: ruby, python]Let's display the global facets (distribution of tags across the whole database):
s.results.facets['global-tags']['terms'].each do |f|
puts "#{f['term'].ljust(10)} #{f['count']}"
end
# ruby 3
# python 1
# php 1
# java 1Now, let's display the facets based on current query (notice that count for articles tagged with 'java' is included, even though it's not returned by our query; count for articles tagged 'php' is excluded, since they don't match the current query):
s.results.facets['current-tags']['terms'].each do |f|
puts "#{f['term'].ljust(10)} #{f['count']}"
end
# ruby 1
# python 1
# java 1Notice, that only variables from the enclosing scope are accessible.
If we want to access the variables or methods from outer scope,
we have to use a slight variation of the DSL, by passing the
search and query objects around.
@query = 'title:T*'
Tire.search 'articles' do |search|
search.query do |query|
query.string @query
end
endQuite often, we need complex queries with boolean logic.
Instead of composing long query strings such as tags:ruby OR tags:java AND NOT tags:python,
we can use the bool
query. In Tire, we build them declaratively.
Tire.search 'articles' do
query do
boolean do
should { string 'tags:ruby' }
should { string 'tags:java' }
must_not { string 'tags:python' }
end
end
endThe best thing about boolean queries is that we can easily save these partial queries as Ruby blocks,
to mix and reuse them later. So, we may define a query for the tags property:
tags_query = lambda do
boolean.should { string 'tags:ruby' }
boolean.should { string 'tags:java' }
endAnd a query for the published_on property:
published_on_query = lambda do
boolean.must { string 'published_on:[2011-01-01 TO 2011-01-02]' }
endNow, we can combine these queries for different searches:
Tire.search 'articles' do
query do
boolean &tags_query
boolean &published_on_query
end
endNote, that you can pass options for configuring queries, facets, etc. by passing a Hash as the last argument to the method call:
Tire.search 'articles' do
query do
string 'ruby python', :default_operator => 'AND', :use_dis_max => true
end
endIf configuring the search payload with blocks feels somehow too weak for you, you can pass
a plain old Ruby Hash (or JSON string) with the query declaration to the search method:
Tire.search 'articles', :query => { :fuzzy => { :title => 'Sour' } }If this sounds like a great idea to you, you are probably able to write your application
using just curl, sed and awk.
Do note again, however, that you're not tied to the declarative block-style DSL Tire offers to you. If it makes more sense in your context, you can use its classes directly, in a more imperative style:
search = Tire::Search::Search.new('articles')
search.query { string('title:T*') }
search.filter :terms, :tags => ['ruby']
search.sort { by :title, 'desc' }
search.facet('global-tags') { terms :tags, :global => true }
# ...
p search.perform.resultsTo debug the query we have laboriously set up like this, we can display the full query JSON for close inspection:
puts s.to_json
# {"facets":{"current-tags":{"terms":{"field":"tags"}},"global-tags":{"global":true,"terms":{"field":"tags"}}},"query":{"query_string":{"query":"title:T*"}},"filter":{"terms":{"tags":["ruby"]}},"sort":[{"title":"desc"}]}Or, better, we can display the corresponding curl command to recreate and debug the request in the terminal:
puts s.to_curl
# curl -X POST "http://localhost:9200/articles/_search?pretty=true" -d '{"facets":{"current-tags":{"terms":{"field":"tags"}},"global-tags":{"global":true,"terms":{"field":"tags"}}},"query":{"query_string":{"query":"title:T*"}},"filter":{"terms":{"tags":["ruby"]}},"sort":[{"title":"desc"}]}'However, we can simply log every search query (and other requests) in this curl-friendly format:
Tire.configure { logger 'elasticsearch.log' }When you set the log level to debug:
Tire.configure { logger 'elasticsearch.log', :level => 'debug' }the JSON responses are logged as well. This is not a great idea for production environment, but it's priceless when you want to paste a complicated transaction to the mailing list or IRC channel.
The Tire DSL tries hard to provide a strong Ruby-like API for the main ElasticSearch features.
By default, Tire wraps the results collection in a enumerable Results::Collection class,
and result items in a Results::Item class, which looks like a child of Hash and Openstruct,
for smooth iterating over and displaying the results.
You may wrap the result items in your own class by setting the Tire.configuration.wrapper
property. Your class must take a Hash of attributes on initialization.
If that seems like a great idea to you, there's a big chance you already have such class.
One would bet it's an ActiveRecord or ActiveModel class, containing model of your Rails application.
Fortunately, Tire makes blending ElasticSearch features into your models trivially possible.
If you're the type with no time for lengthy introductions, you can generate a fully working
example Rails application, with an ActiveRecord model and a search form, to play with
(it even downloads ElasticSearch itself, generates the application skeleton and leaves you with
a Git repository to explore the steps and the code):
$ rails new searchapp -m https://github.com/karmi/tire/raw/master/examples/rails-application-template.rb
For the rest of us, let's suppose you have an Article class in your Rails application.
To make it searchable with Tire, just include it:
class Article < ActiveRecord::Base
include Tire::Model::Search
include Tire::Model::Callbacks
endWhen you now save a record:
Article.create :title => "I Love ElasticSearch",
:content => "...",
:author => "Captain Nemo",
:published_on => Time.nowit is automatically added into an index called 'articles', because of the included callbacks. (You may want to skip them in special cases, like when your records are indexed via some external mechanism, let's say a CouchDB or RabbitMQ river.
The document attributes are indexed exactly as when you call the Article#to_json method.
Now you can search the records:
Article.search 'love'OK. This is where the search game stops, often. Not here.
First of all, you may use the full query DSL, as explained above, with filters, sorting, advanced facet aggregation, highlighting, etc:
Article.search do
query { string 'love' }
facet('timeline') { date :published_on, :interval => 'month' }
sort { by :published_on, 'desc' }
endSecond, dynamic mapping is a godsend when you're prototyping. For serious usage, though, you'll definitely want to define a custom mapping for your models:
class Article < ActiveRecord::Base
include Tire::Model::Search
include Tire::Model::Callbacks
mapping do
indexes :id, :type => 'string', :index => :not_analyzed
indexes :title, :type => 'string', :analyzer => 'snowball', :boost => 100
indexes :content, :type => 'string', :analyzer => 'snowball'
indexes :author, :type => 'string', :analyzer => 'keyword'
indexes :published_on, :type => 'date', :include_in_all => false
end
endIn this case, only the defined model attributes are indexed. The mapping declaration creates the
index when the class is loaded or when the importing features are used, and only when it does not yet exist.
Chances are, you want to declare also a custom settings for the index, such as set the number of shards,
replicas, or create elaborate analyzer chains, such as the hipster's choice: ngrams.
In this case, just wrap the mapping method in a settings one, passing it the settings as a Hash:
class URL < ActiveRecord::Base
include Tire::Model::Search
include Tire::Model::Callbacks
settings :number_of_shards => 1,
:number_of_replicas => 1,
:analysis => {
:filter => {
:url_ngram => {
"type" => "nGram",
"max_gram" => 5,
"min_gram" => 3 }
},
:analyzer => {
:url_analyzer => {
"tokenizer" => "lowercase",
"filter" => ["stop", "url_ngram"],
"type" => "custom" }
}
} do
mapping { indexes :url, :type => 'string', :analyzer => "url_analyzer" }
end
endIt may well be reasonable to wrap the index creation logic declared with Tire.index('urls').create
in a class method of your model, in a module method, etc, so have better control on index creation when
bootstrapping your application with Rake tasks or when setting up the test suite.
Tire will not hold that against you.
You may have just stopped wondering: what if I have my own settings class method defined?
Or what if some other gem defines settings, or some other Tire method, such as update_index?
Things will break, right? No, they won't.
In fact, all this time you've been using only proxies to the real Tire methods, which live in the tire
class and instance methods of your model. Only when not trampling on someone's foot — which is the majority
of cases —, will Tire bring its methods to the namespace of your class.
So, instead of writing Article.search, you could write Article.tire.search, and instead of
@article.update_index you could write @article.tire.update_index, to be on the safe side.
Let's have a look on an example with the mapping method:
class Article < ActiveRecord::Base
include Tire::Model::Search
include Tire::Model::Callbacks
tire.mapping do
indexes :id, :type => 'string', :index => :not_analyzed
# ...
end
endOf course, you could also use the block form:
class Article < ActiveRecord::Base
include Tire::Model::Search
include Tire::Model::Callbacks
tire do
mapping do
indexes :id, :type => 'string', :index => :not_analyzed
# ...
end
end
endInternally, Tire uses these proxy methods exclusively. When you run into issues,
use the proxied method, eg. Article.tire.mapping, directly.
When you want a tight grip on how the attributes are added to the index, just
implement the to_indexed_json method in your model.
The easiest way is to customize the to_json serialization support of your model:
class Article < ActiveRecord::Base
# ...
include_root_in_json = false
def to_indexed_json
to_json :except => ['updated_at'], :methods => ['length']
end
endOf course, it may well be reasonable to define the indexed JSON from the ground up:
class Article < ActiveRecord::Base
# ...
def to_indexed_json
names = author.split(/\W/)
last_name = names.pop
first_name = names.join
{
:title => title,
:content => content,
:author => {
:first_name => first_name,
:last_name => last_name
}
}.to_json
end
endThe results returned by Article.search are wrapped in the aforementioned Item class, by default.
This way, we have a fast and flexible access to the properties returned from ElasticSearch (via the
_source or fields JSON properties). This way, we can index whatever JSON we like in ElasticSearch,
and retrieve it, simply, via the dot notation:
articles = Article.search 'love'
articles.each do |article|
puts article.title
puts article.author.last_name
endThe Item instances masquerade themselves as instances of your model within a Rails application
(based on the _type property retrieved from ElasticSearch), so you can use them carefree;
all the url_for or dom_id helpers work as expected.
If you need to access the “real” model (eg. to access its assocations or methods not stored in ElasticSearch), just load it from the database:
puts article.load(:include => 'comments').comments.sizeYou can see that Tire stays as far from the database as possible. That's because it believes
you have most of the data you want to display stored in ElasticSearch. When you need
to eagerly load the records from the database itself, for whatever reason,
you can do it with the :load option when searching:
# Will call `Article.search [1, 2, 3]`
Article.search 'love', :load => trueInstead of simple true, you can pass any options for the model's find method:
# Will call `Article.search [1, 2, 3], :include => 'comments'`
Article.search :load => { :include => 'comments' } do
query { string 'love' }
endNote that Tire search results are fully compatible with will_paginate,
so you can pass all the usual parameters to the search method in the controller:
@articles = Article.search params[:q], :page => (params[:page] || 1)OK. Chances are, you have lots of records stored in your database. How will you get them to ElasticSearch? Easy:
Article.index.import Article.allThis way, however, all your records are loaded into memory, serialized into JSON, and sent down the wire to ElasticSearch. Not practical, you say? You're right.
Provided your model implements some sort of pagination — and it probably does —, you can just run:
Article.importIn this case, the Article.paginate method is called, and your records are sent to the index
in chunks of 1000. If that number doesn't suit you, just provide a better one:
Article.import :per_page => 100Any other parameters you provide to the import method are passed down to the paginate method.
Are we saying you have to fiddle with this thing in a rails console or silly Ruby scripts? No.
Just call the included Rake task on the commandline:
$ rake environment tire:import CLASS='Article'You can also force-import the data by deleting the index first (and creating it with mapping
provided by the mapping block in your model):
$ rake environment tire:import CLASS='Article' FORCE=trueWhen you'll spend more time with ElasticSearch, you'll notice how index aliases are the best idea since the invention of inverted index. You can index your data into a fresh index (and possibly update an alias once everything's fine):
$ rake environment tire:import CLASS='Article' INDEX='articles-2011-05'OK. All this time we have been talking about ActiveRecord models, since
it is a reasonable Rails' default for the storage layer.
But what if you use another database such as MongoDB, another object mapping library, such as Mongoid?
Well, things stay mostly the same:
class Article
include Mongoid::Document
field :title, :type => String
field :content, :type => String
include Tire::Model::Search
include Tire::Model::Callbacks
# Let's use a different index name so stuff doesn't get mixed up
#
index_name 'mongo-articles'
# These Mongo guys sure do some funky stuff with their IDs
# in +serializable_hash+, let's fix it.
#
def to_indexed_json
self.to_json
end
end
Article.create :title => 'I Love ElasticSearch'
Article.search 'love'Tire does not care what's your primary data storage solution, if it has an ActiveModel-compatible adapter. But there's more.
Tire implements not only searchable features, but also persistence features. This means you can use a Tire model instead of your database, not just for searching your database. Why would you like to do that?
Well, because you're tired of database migrations and lots of hand-holding with your
database to store stuff like { :name => 'Tire', :tags => [ 'ruby', 'search' ] }.
Because what you need is to just dump a JSON-representation of your data into a database and
load it back when needed.
Because you've noticed that searching your data is a much more effective way of retrieval
then constructing elaborate database query conditions.
Because you have lots of data and want to use ElasticSearch's
advanced distributed features.
To use the persistence features, just include the Tire::Persistence module in your class and define the properties (like with CouchDB- or MongoDB-based models):
class Article
include Tire::Model::Persistence
include Tire::Model::Search
include Tire::Model::Callbacks
validates_presence_of :title, :author
property :title
property :author
property :content
property :published_on
endOf course, not all validations or ActionPack helpers will be available to your models,
but if you can live with that, you've just got a schema-free, highly-scalable storage
and retrieval engine for your data.
This will result in Article instances being stored in an index called 'test_articles' when used in tests but in the index 'development_articles' when used in the development environment.
Please be sure to peruse the integration test suite for examples of the API and ActiveModel integration usage.
The tire-contrib project contains additions and extensions to the Tire functionality.
Tire is already used in production by its authors. Nevertheless, it's not considered finished yet.
There are todos, plans and ideas, some of which are listed below, in the order of importance:
- Proper RDoc annotations for the source code
- Statistical facets
- Geo Distance facets
- Index aliases management
- Analyze API support
- Embedded webserver to display statistics and to allow easy searches
Check out other ElasticSearch clients.
You can send feedback via e-mail or via Github Issues.