title: Validating copy of large amount data
body: <p>I have written an algorithm which basically copies large amount of data from Oracle database to mysql database. Copying is done by column date. It takes about one day to copy items which I need. It copies about 5 000 000 items.</p>
  
  <p>The question is, is there a possibility to check if the data copied to mysql database is valid and is exactly the same. Checking only the count of items does not solve this problem, because there was noticed some items with null value instead of some values presented in oracle databases.</p>