Delete large Redis hashes with Ruby and Resque

gistfile1.rb

$redis = Redis.new

class SafeHashDelete
  @queue = :garbage_collection

  BATCH_SIZE = 100

  # Rename the key and queue for deletion
  def self.delete(key)
    newkey = "gc:hashes:#{$redis.incr("gc:index")}"
    $redis.rename(key, newkey)
    Resque.enqueue(self, newkey)
  end

  # Delete fields from the hash in batches
  def self.perform(key)
    cursor = "0"
    loop do
      cursor, fields = $redis.hscan(key, cursor, count: BATCH_SIZE)
      hkeys = fields.map { |pair| pair[0] }
      $redis.hdel(key, hkeys) if hkeys.size > 0
      break if cursor == "0"
    end
  end
end

# Example:
#
#   SafeHashDelete.delete("my.large.hash")