Rails DB Sequence Generation

sequence_gen

class CreateMerchantUniqIdGens < ActiveRecord::Migration
  def change
    create_table :merchant_uniq_id_gens do |t|
      t.integer :count, :null => false
    end

    # Set initial count to 100
    single_row = MerchantUniqIdGen.new
    single_row.count = 100
    single_row.save!
  end
end


class MerchantUniqIdGen < ActiveRecord::Base
  def self.next
    curr_count = 0;
    MerchantUniqIdGen.transaction do
      id_gen = MerchantUniqIdGen.lock(true).first
      id_gen.count += 1
      curr_count = id_gen.count
      id_gen.save!
    end
    curr_count
  end
end

puts MerchantUniqIdGen.next