title: Tips to migrate huge volume of data from one table to another?
body: <p>We have to split one table into two.</p>
  <p>Our currently working script looks like this:</p>
  <ol>
  <li>disable the constraints of the new tables</li>
  <li><code>INSERT INTO newTable1 SELECT... FROM oldTable</code></li>
  <li><code>INSERT INTO newTable2 SELECT... FROM oldTable WHERE fieldX IS NOT NULL</code></li>
  <li>re-enable constraints</li>
  </ol>
  <p>In the mean time we also investigate the usage of <a href="https://docs.oracle.com/database/121/VLDBG/GUID-2627DC19-7EBE-4C45-A758-711BDB5E37EC.htm" rel="nofollow noreferrer">parallelism</a> (so far in our tests there were no gains for some reason...).</p>
  <p>Apart from that, what else could we use to make a safe and fast migration in PROD?</p>