title: Defering drop table after exchange partition
body: <p>I have two tables:</p>
  
  <p><code>ld_tbl</code> - a partitioned table.</p>
  
  <p><code>tgt_tabl</code> - a non partitioned table.</p>
  
  <p>In my program I'm executing</p>
  
  <pre><code>alter table ld_tbl exchange partition prt with table tgt_table;
  </code></pre>
  
  <p>and after the exchange has finished I'm executing a drop to the <code>ld_tbl</code>.</p>
  
  <p>The problem is that if someone has fired a query through the <code>tgt_tabl</code> it throws exception:</p>
  
  <blockquote>
    <p>ORA-00813: object no longer exists</p>
  </blockquote>
  
  <p>Even I drop only the <code>ld_tbl</code> and didn't touch the <code>tgt_tabl</code>. After several tests, I'm sure that it's the drop which causes the exception. According to this information: <a href="https://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:9509565700346771185" rel="nofollow noreferrer">Object no longer exists</a>, the solution is to defer the drop.</p>
  
  <p>My question is: how much time is needed between the drop and the exchange? How can I know that operation like drop will not hurt the other table?</p>
  
  <p>Thanks.</p>