user_high_score.rb

class UserHighScore < ActiveRecord::Base
  belongs_to :user
  belongs_to :high_score_partition
  attr_accessible :score
  after_save do
    partition = HighScorePartition.where("(min < ? AND ? > max)", self.score, self.score).first("LOCK IN SHARE MODE")
    # Not partition if cheet?
    raise "Score not range partition" unless partition
    # Not modify
    return true partition.id == self.high_score_partition.id
    # Remove user for old pertition
    self.partition.decrement! :user_count
    # Add user for new partition
    partition.increment! :user_count
    # New partition
    self.high_score_partition = partition
    self.save!
  end
end