redis memory optimisation

gistfile1.txt

#  def to_base62
#    Base62.encode(to_s)
#  end

2.4.1 :001 > redis = Redis.new
 => #<Redis client v4.0.1 for redis://127.0.0.1:6379/0> 
2.4.1 :002 > redis.flushdb
2.4.1 :003 > redis.info(:memory)['used_memory_human']
 => "670.55K" 
2.4.1 :004 > redis.pipelined { 100000.times{|i| redis.incr( "user:#{i}" ) }; }; :done
2.4.1 :005 > redis.info(:memory)['used_memory_human']
 => "7.76M" 
2.4.1 :006 > redis.flushdb
2.4.1 :007 > redis.pipelined { 100000.times{|i| redis.incr( "u:#{i.to_base62}" ) }; }; :done
2.4.1 :008 > redis.info(:memory)['used_memory_human']
 => "6.23M" 
2.4.1 :010 > (670.kilobytes.to_f / 1.megabyte).round(2)
 => 0.65 
2.4.1 :011 > ((7.76 - 0.65)/(6.23 - 0.65)).round(2)
 => 1.27