mass_insert_uniq.rb

module MassInsertUniq
  extend ActiveSupport::Concern

  included do
    include PluckHash
  end

  module ClassMethods
    def mass_insert_uniq(attributes, insert_scope: -> { self })
      return if attributes.blank?
      attributes = Array(attributes)
      existent = insert_scope.call.pluck_hash(*attributes.first.keys)
      attributes = attributes - existent

      if attributes.any?
        connection.insert(sanitize_sql(sanitize_array(attributes)))
      end
    end

    private
    def sanitize_array(attributes)
      names = attributes_name(attributes)
      values = attributes_value(attributes)

      ["INSERT INTO #{table_name} (#{names.join(', ')}) VALUES #{value_signs(attributes)}", *values.flatten]
    end

    def value_signs(attributes)
      Array.new(attributes.size, question_signs(attributes)).join(', ')
    end

    def question_signs(attributes)
      total = attributes.first.size + 2
      signs = Array.new(total, '?').join(', ')
      "(#{signs})"
    end

    def attributes_name(hash_collection)
      hash_collection.first.keys + %w(created_at updated_at)
    end

    def attributes_value(hash_collection)
      time = Time.now.utc.to_s(:db)
      hash_collection.map { |hash| hash.values + [time, time] }
    end
  end
end

pluck_hash.rb

module PluckHash
  extend ActiveSupport::Concern

  module ClassMethods
    def pluck_hash(*keys)
      pluck(*keys).map{|pa| Hash[keys.zip(pa)]}
    end
  end
end