Mr. Mongo

MapReduce framework for MongoDB using Ruby DSL

Installation

Add this line to your application's Gemfile:

gem 'mr_mongo'

And then execute:

$ bundle

Or install it yourself as:

$ gem install mr_mongo

Usage

mr_mongo command

$ bundle exec mr_mongo
Commands:
  mr_mongo exec            # executes MapReduce
  mr_mongo exec_on_memory  # executes MapReduce on memory
  mr_mongo help [COMMAND]  # Describe available commands or one specific command

NOTICE

The result of exec_on_memory may be massive, so it's preferable to use for small collections as testing.

Defining MapReduce job using DSL

Following is word-count example using Mr. Mongo DSL

set :collection, 'texts'
set :out, {replace: 'word_counts'}

__END__

Dynamic Parameters

sub-commands exec and exec_on_memory accepts Dynamic Parameters by --params option.

--params can be specified as JSON hash.

$ bundle exec mr_mongo exec some_map_reduce.rb --params '{"date":"2013-02-01"}'

In DSL, Dynamic Parameters can be get with #params method.

set :collection, 'accesses'
set :query, {date: params['date']} if params['date']

__END__

Default Parameter

Default Parameter can be set with #default_param method

default_param 'date', '2013-02-01'

# => params will be {"date" => "2013-02-01"} by default.

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request