title: reading txt file into perl's hash
body: <p>Hej sharp minds!</p>
  
  <p>I need to load text file into hash. One line is the key, next line is the value. And that repeats several million times. Any suggestions how to do it in the best way?</p>
  
  <p>And how much memory the hash table would need if let's say key is 15 characters and value is 50 characters?</p>
  
  <p>Thanks</p>