Blueshift

The Amazon Redshift adapter for Sequel

Installation

Add this line to your application's Gemfile:

gem 'blue-shift'

And then execute:

$ bundle

Or install it yourself as:

$ gem install blue-shift

Usage

create_table Options:

• :distkey => column name

  The Distribution Key. When specified, the :diststyle is set to :key unless otherwise specified

• :diststyle => :even (implicit default), :key, or :all

  The Distribution Style. When :distkey is also specified, only :key DISTSTYLE is supported by Redshift and will be ignored by Postgres

• :sortkeys => a list of column names

  The Sort Keys. Depending on your :sortstyle, there is a maximum number of sortkeys that you can specify: Compound: up to 400 sortkeys Interleaved: up to 8 sortkeys

• :sortstyle => :compound (default) or :interleaved

  The Sort Style. This option has no effect unless :sortkeys is also specified

For example:

create_table :chocolates, distkey: :region, diststyle: :key, sortkeys: [:richness, :organic], sortstyle: :interleaved do
    String  :region
    Integer :richness
    boolean :organic
    String  :description
end

You can also redeclare the sortkeys for an existing table by using the optimize_table method. This is reconstructive, no additive. For example:

optimize_table :chocolates, sortkeys: [:organic, :region], distkey: :region 

Migrations

Blueshift unifies migrations for your Postgres and Redshift databases into one file. Postgres migrations and Redshift migrations use Sequel.

Blueshift.migration do
  up do
    # applies to Postgres only
  end

  down do
    # applies to Postgres only
  end

  redup do
    # applies to Redshift only
  end

  reddown do
    # applies to Redshift only
  end
end

If you want your migration to only run on Postgres, you can specify an empty block:

Blueshift.migration do
  up do
    # applies to Postgres only
  end

  down do
    # applies to Postgres only
  end

  redup {}

  reddown {}
end

Transactions

By default, each migration runs within a transaction. You can manually specify to disable transactions on a per migration basis. For example, if you want to not force transaction use for a particular migration, call the no_transaction method in the Blueshift.migration block:

Blueshift.migration do
  no_transaction
  up do
    # ...
  end
end

This is necessary in some cases, such as when attempting to use CREATE INDEX CONCURRENTLY on PostgreSQL (which supports transactional schema, but not that statement inside a transaction).

Also, because each optimize_table call gets run within its own transaction, you should probably use no_transaction in migrations that use that in order to prevent starting multiple transactions within one another.

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also 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, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/influitive/blueshift.