Parts

Parts is an ActiveRecord migrations and model helpers for creating and managing PostgreSQL 11+ declarative partitions!. This project is heavily influnced from pg_party gem.

Features:

• Migration methods for partition specific database operations
• Model methods for querying partitioned data
• Model methods for creating adhoc partitions

Limitations:

• Partition tables are not represented correctly in db/schema.rb ? please use the :sql schema format
• Complex partition keys are not supported yet.

Installation

Add this line to your application's Gemfile:

gem 'parts'

And then execute:

$ bundle

Or install it yourself as:

$ gem install parts

Usage

Migration Examples

Create range partition on created_at with two child partitions:

class CreateSomeRangeRecord < ActiveRecord::Migration[5.0]
  def up
    current_date = Date.current

    create_range_parent :some_range_records, :created_at do |t|
      t.text :some_value
      t.timestamps
    end

    add_index :some_range_records, :some_value

    create_range_child_of :some_range_records, 
        "some_range_records_#{current_date.strftime('y%Ym%mw%V')}",
        start_range: current_date.beginning_of_week,
        end_range: current_date.next_week.beginning_of_week

    next_date = current_date.next_week

    create_range_child_of :some_range_records,
        "some_range_records_#{next_date.strftime('y%Ym%mw%V')}",
        start_range: next_date.beginning_of_week,
        end_range: next_date.next_week.beginning_of_week
  end
end

Create list partition on status with two child partitions, second child partition some_list_records_inactive is further range partitioned on created_at.

class CreateSomeListRecord < ActiveRecord::Migration[5.0]
  def up
    create_list_parent :some_list_records, :status do |t|
      t.text :some_value
      t.string :status

      t.timestamps
    end

    create_list_child_of :some_list_records, 
        :some_list_records_active,
        :active

    create_sub_parent :some_list_records_inactive, 
        parent_table_name: :some_list_records, 
        parent_type: :list,
        parent_values: :inactive,
        type: :range,
        partition_key: :created_at

    current_date = Date.current

    create_range_child_of :some_list_records_inactive, 
        "some_list_records_inactive_#{current_date.strftime('y%Ym%mw%V')}",
        start_range: current_date.beginning_of_week,
        end_range: current_date.next_week.beginning_of_week

    next_date = current_date.next_week

    create_range_child_of :some_list_records_inactive,
        "some_list_records_inactive_#{next_date.strftime('y%Ym%mw%V')}",
        start_range: next_date.beginning_of_week,
        end_range: next_date.next_week.beginning_of_week
  end
end

Create hash partition on id with 10 child partitions:

class CreateSomeRangeRecord < ActiveRecord::Migration[5.0]
  def up
    create_hash_parent :some_huge_table, :id do |t|
        t.text :some_value
        t.timestamps
    end

    add_index :some_range_records, :some_value

    # Creates 10 child hash table
    create_hash_children_of :some_huge_table, 10
  end
end

Attach an existing table to a range partition:

class AttachRangePartition < ActiveRecord::Migration[5.0]
  def up
    current_date = Date.current

    attach_range_child_to \
      :some_existing_range_parent_partition_table,
      :some_range_records,
      start_range: current_date,
      end_range: current_date + 1.day
  end
end

Attach an existing table to a list partition:

class AttachListPartition < ActiveRecord::Migration[5.0]
  def up
    attach_list_child_to \
      :some_existing_list_parent_partition_table,
      :some_list_records,
      values: 'active'
  end
end

Detach a child table from any partition:

class DetachPartition < ActiveRecord::Migration[5.0]
  def up
    detach_child_from :parent_table, :child_table
  end
end

Model Examples

Extend your model to support partitioning methods within the model:

class SomeRangeRecord < ApplicationRecord
    extend Parts::ModelMethods
end

Create child partition from range partition model:

current_date = Date.current

SomeRangeRecord.create_range_child("some_range_record_xyz", start_range: current_date + 1.day, end_range: current_date + 2.days)

Create child partition from list partition model:

SomeListRecord.create_list_child("some_list_record_active", :active)

List currently attached partitions:

SomeRangeRecord.partitions

SomeListRecord.partitions

Retrieve ActiveRecord model class scoped to a child partition:

SomeRangeRecord.in_partition(:some_range_records_partition_name)

SomeListRecord.in_partition(:some_list_records_partition_name)

#check for partitions within sub-partitions

SomeListRecord.in_partition(:some_list_sub_parent_partition).partitions

Check if any model is partitioned:

SomeNonPartitionedTable.partitioned?
# => false

SomePartitionedTable.partitioned?
# => true

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/[USERNAME]/parts. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the Parts project?s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.