title: redis memory efficiency
body: <p>I want to load data with 4 columns and 80 millon rows in MySQL on Redis, so that I can reduce fetching delay.</p>
  
  <p>However, when I try to load all the data, it becomes 5 times larger.</p>
  
  <p>The original data was 3gb (when exported to csv format), but when I load them on Redis, it takes 15GB... it's too large for our system.</p>
  
  <p>I also tried different datatypes - </p>
  
  <p>1) 'table_name:row_number:column_name' -> string 
  2) 'table_name:row_number' -> hash</p>
  
  <p>but all of them takes too much.</p>
  
  <p>am I missing something?</p>
  
  <p>added)</p>
  
  <p>my data have 4 col - (user id(pk), count, created time, and a date)</p>