# MixedGauge
[](https://travis-ci.org/taiki45/mixed_gauge) [](https://coveralls.io/r/taiki45/mixed_gauge?branch=master) [](https://codeclimate.com/github/taiki45/mixed_gauge) [](http://badge.fury.io/rb/mixed_gauge)
An ActiveRecord extension for database sharding.
## Installation
Add this line to your application's Gemfile:
```ruby
gem 'mixed_gauge'
```
And then execute:
$ bundle
Or install it yourself as:
$ gem install mixed_gauge
## Usage
Add additional database connection config to `database.yml`.
```yaml
# database.yml
production_user_001:
adapter: mysql2
username: user_writable
host: db-user-001
production_user_002:
adapter: mysql2
username: user_writable
host: db-user-002
production_user_003:
adapter: mysql2
username: user_writable
host: db-user-003
production_user_004:
adapter: mysql2
username: user_writable
host: db-user-004
```
Configure slots (virtual node for cluster) then assign slots to real node.
```ruby
MixedGauge.configure do |config|
config.define_cluster(:user) do |cluster|
# When slots per node * max nodes per cluster = (2 ** 10) * (2 ** 10)
cluster.define_slots(1..1048576)
cluster.register(1..262144, :production_user_001)
cluster.register(262145..524288, :production_user_002)
cluster.register(524289..786432, :production_user_003)
cluster.register(786433..1048576, :production_user_004)
end
end
```
Include `MixedGauge::Model` to your model class, specify cluster name for the
model, specify distkey which determine nodes to store.
```ruby
class User < ActiveRecord::Base
include MixedGauge::Model
use_cluster :user
def_distkey :email
end
```
Use `.get` to retrive single model class which is connected to proper
database node. Use `.put!` to create new record to proper database node.
`.all_shards` enables you to all model class which is connected to all
database nodes in the cluster.
```ruby
User.put!(email: 'alice@example.com', name: 'alice')
alice = User.get('alice@example.com')
alice.age = 1
alice.save!
User.all_shards.flat_map {|m| m.where(name: 'alice') }.compact
```
## Development
After checking out the repo, run `bin/setup` to install dependencies. Then, run `bin/console` for an interactive prompt that will allow you to experiment.
To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release` to create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).
## Contributing
1. Fork it ( https://github.com/[my-github-username]/mixed_gauge/fork )
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 a new Pull Request