title: distribution transaction lock in oracle database
body: <p>I have some question around transaction lock in oracle database. What I have found out so far is that:</p>
  
  <p><strong>Cause</strong>: The time to wait on a lock in a distributed transaction has been exceeded. This time is specified in the initialization parameter <code>DISTRIBUTED_LOCK_TIMEOUT</code>.</p>
  
  <p><strong>Action</strong>: This situation is treated as a deadlock and the statement was rolled back. To set the time-out interval to a longer interval, adjust the initialization parameter <code>DISTRIBUTED_LOCK_TIMEOUT</code>, then shut down and restart the instance. </p>
  
  <p>Some other things that I want to know in more details are things like:</p>
  
  <ol>
  <li><p>It is mentioned that a lock in 'distributed transaction' happened. So what kind of database operation that can cause this ? Updating a record ? Selecting a record ? </p></li>
  <li><p>What does 'Distributed' means anyway. I have seen this term coined all over the place, but I can't seem to deduce what it means.</p></li>
  <li><p>What can we do to reduce instances of such lock ?</p></li>
  </ol>