RailsEventStore/cqrs-es-sample-with-res

class CreateEventStoreEvents < ActiveRecord::Migration[4.2]
  def change
    postgres = ActiveRecord::Base.connection.adapter_name == "PostgreSQL"
    sqlite   = ActiveRecord::Base.connection.adapter_name == "SQLite"
    rails_42 = Gem::Version.new(ActiveRecord::VERSION::STRING) < Gem::Version.new("5.0.0")
    enable_extension "pgcrypto" if postgres
    create_table(:event_store_events_in_streams, force: false) do |t|
      t.string      :stream,      null: false
      t.integer     :position,    null: true
      if postgres
        t.references :event, null: false, type: :uuid
      else
        t.references :event, null: false, type: :string
      end
      t.datetime    :created_at,  null: false
    end
    add_index :event_store_events_in_streams, [:stream, :position], unique: true
    add_index :event_store_events_in_streams, [:created_at]
    add_index :event_store_events_in_streams, [:stream, :event_id], unique: true

    if postgres
      create_table(:event_store_events, id: :uuid, default: "gen_random_uuid()", force: false) do |t|
        t.string      :event_type,  null: false
        t.text        :metadata
        t.text        :data,        null: false
        t.datetime    :created_at,  null: false
      end
    else
      create_table(:event_store_events, id: false, force: false) do |t|
        t.string :id, limit: 36, primary_key: true, null: false
        t.string      :event_type,  null: false
        t.text        :metadata
        t.text        :data,        null: false
        t.datetime    :created_at,  null: false
      end
      if sqlite && rails_42
        add_index :event_store_events, :id, unique: true
      end
    end
    add_index :event_store_events, :created_at
  end
end