# Massive Record Massive Record is an ORM for HBase. It currently uses Thrift to communicate with HBase and will in time support other forms for communicating with Hbase. See introduction to HBase model architecture: http://wiki.apache.org/hadoop/Hbase/HbaseArchitecture Understanding terminology of Table / Row / Column family / Column / Cell: http://jimbojw.com/wiki/index.php?title=Understanding_Hbase_and_BigTable ## Installation First of all: Please make sure you are using Ruby 1.9.2. For now, we are only ensuring that Massive Record works on that Ruby version, and we know it has some problems with 1.8.7. gem install massive_record ### Ruby on Rails Add the following Gems in your Gemfile: gem 'massive_record' Create an config/hbase.yml file with the following content: defaults: &defaults host: somewhere.compute.amazonaws.com # No 'http', it's a Thrift connection port: 9090 development: <<: *defaults test: <<: *defaults production: <<: *defaults ## Usage There are two ways for using the Massive Record library. At the highest level we have ORM. This is Active Model compliant and makes it easy to use. The second way of doing things is working directly against the wrapper (soon to be called adapter). ### ORM Both MassiveRecord::ORM::Table and MassiveRecord::ORM::Column do now have some functionality which you can expect from an ORM. This includes: - An initializer which takes attribute hash and assigns them to your object. - Write and read methods for the attributes - Validations, as you expect from an ActiveRecord. - Callbacks, as you expect from an ActiveRecord. - Information about changes on attributes. - Casting of attributes - Serialization of array / hashes - Timestamps like created_at and updated_at. Updated at will always be available, created_at must be defined. See example down: - Finder scopes. Like: Person.select(:only_columns_from_this_family).limit(10).collect(&:name) - Ability to set a default scope. Tables also have: - Persistencey method calls like create, save and destroy (but they do not actually save things to hbase) - Easy access to adapter's connection via Person.connection - Easy access to adapter's hbase table via Person.table - Finder method, like Person.find("an_id"), Person.find("id1", "id2"), Person.all etc - Save / update methods - Auto-creation of table and column families on save if table does not exists. - Destroy records - Relations: See MassiveRecord::ORM::Relations::Interface ClassMethods for documentation Here is an example of usage, both for Table and Column: class Person < MassiveRecord::ORM::Table references_one :boss, :class_name => "Person", :store_in => :info references_one :attachment, :polymorphic => true references_many :friends, :store_in => :info references_many :cars, :records_starts_from => :cars_start_id default_scope select(:info) column_family :info do field :name field :email field :phone_number field :points, :integer, :default => 0 field :date_of_birth, :date, :allow_nil => false # Defaults to today field :newsletter, :boolean, :default => false field :type # Used for single table inheritance field :in_the_future, :time, :default => Proc.new { 2.hours.from_now } timestamps # ..or field :created_at, :time end column_family :misc do field :with_a_lot_of_uninteresting_data end validates_presence_of :name, :email validates_format_of :email, :with => /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\Z/i # Returns the id the scanner should start from in the Car table # to fetch cars related to this person def cars_start_id id+'-' end end class Friend < Person # This one will be stored in Person's table with it's type set to Friend. # Calling Person.all will return object back as a Friend. end class Address < MassiveRecord::ORM::Column field :street field :number, :integer field :nice_place, :boolean, :default => true end ### Related gems We have developed some gems which adds support for MassiveRecord. These are: #### ORM Adapter https://github.com/CompanyBook/orm_adapter Used by Devise. I guess we'll might release the code used to get Devise support in MR. #### Database Cleaner https://github.com/CompanyBook/database_cleaner User by for instance Cucumber and ourself with Rspec. #### Sunspot Rails https://github.com/CompanyBook/sunspot_massive_record Makes it easier to make things searchable with solr. ## Wrapper (adapter) API You can, if you'd like, work directly against the adapter. # Init a new connection with HBase conn = MassiveRecord::Wrapper::Connection.new(:host => 'localhost', :port => 9090) conn.open # OR init a connection using the config/hbase.yml file with Rails conn = MassiveRecord::Wrapper::Base.connection # Fetch tables name conn.tables # => ["companies", "news", "webpages"] # Init a table table = MassiveRecord::Wrapper::Table.new(conn, :people) # Add a column family column = MassiveRecord::Wrapper::ColumnFamily.new(:info) table.column_families.push(column) # Or bulk add column families table.create_column_families([:friends, :misc]) # Create the table table.save # will raise an exception if the table already exists # Fetch column families from the database table.fetch_column_families # => [ColumnFamily#RTY4424, ColumnFamily#R475424, ColumnFamily#GHJ9424] table.column_families.collect(&:name) # => ["info", "friends", "misc"] # Add a new row row = MassiveRecord::Wrapper::Row.new row.id = "my_unique_id" row.values = { :info => { :first_name => "H", :last_name => "Base", :email => "h@base.com" } } row.table = table row.save # Fetch rows table.first # => MassiveRecord#ID1 table.all(:limit => 10) # => [MassiveRecord#ID1, MassiveRecord#ID2, ...] table.find("ID2") # => MassiveRecord#ID2 table.find(["ID1", "ID2"]) # => [MassiveRecord#ID1, MassiveRecord#ID2] table.all(:limit => 3, :start => "ID2") # => [MassiveRecord#ID2, MassiveRecord#ID3, MassiveRecord#ID4] # Manipulate rows table.first.destroy # => true # Remove the table table.destroy ## Planned work - Rename Wrapper to Adapter, and make it easy to switch from Thrift to another way of communicating with Hbase. - Embedded objects. - Cache the decoded values of attributes, not use the value_is_already_decoded?. This will fix possible problem with YAML as coder backend. - Implement other Adapters, for instance using jruby and the Java API. ## Contribute If you want to contribute feel free to fork this project :-) Make a feature branch, write test, implement and make a pull request. ### Getting started git clone git://github.com/CompanyBook/massive_record.git (or the address to your fork) cd massive_record bundle install Next up you need to add a config.yml file inside of spec/ which contains something like: host: url.to-a.thrift.server port: 9090 table: massive_record_test_table You should now be able to run `rspec spec/` ### Play with it in the console Checkout the massive_record project and install it as a Gem : cd massive_record/ bundle console ruby-1.9.2-p0 > Bundler.require => [ , , , , ] ruby-1.9.2-p0 > MassiveRecord::VERSION => "0.0.1" ### Clean HBase database between each test We have created a helper module MassiveRecord::Rspec::SimpleDatabaseCleaner which, when included into rspec tests, will clean the database for ORM records between each test case. You can also take a look into spec/support/mock_massive_record_connection.rb for some functionality which will mock a hbase connection making it easier (faster) to test code where no real database is needed. ## More Information and Resources ### Thrift API Ruby Library using the HBase Thrift API. http://wiki.apache.org/hadoop/Hbase/ThriftApi The generated Ruby files can be found under lib/massive_record/thrift/ The whole API (CRUD and more) is present in the Client object (Apache::Hadoop::Hbase::Thrift::Hbase::Client). The client can be easily initialized using the MassiveRecord connection : conn = MassiveRecord::Wrapper::Connection.new(:host => 'localhost', :port => 9090) conn.open client = conn.client # Do whatever you want with the client object ### Q&A How to add a new column family to an existing table? # Connect to the HBase console on the server itself and enter the following code : disable 'companies' alter 'companies', { NAME => 'new_collumn_familiy' } enable 'companies' Copyright (c) 2011 Companybook, released under the MIT license