discourse/app/models/draft_sequence.rb

class DraftSequence < ActiveRecord::Base
  def self.next!(user,key)
    user_id = user
    user_id = user.id unless user.class == Fixnum
    h = { user_id: user_id, draft_key: key }
    c = DraftSequence.where(h).first
    c ||= DraftSequence.new(h)
    c.sequence ||= 0
    c.sequence += 1
    c.save
    c.sequence
  end

  def self.current(user, key)
    return nil unless user

    user_id = user
    user_id = user.id unless user.class == Fixnum

    # perf critical path
    r = exec_sql('select sequence from draft_sequences where user_id = ? and draft_key = ?', user_id, key).values

    r.length.zero? ? 0 : r[0][0].to_i
  end
end