title: Any idea about these extra tables in my development schema?
body: <p>I'm on Oracle 11gR2. In Development environment I have a schema DEV3 and I'm seeing a lot of extra tables.  I'm wondering what or who created these tables.
  If anyone has any idea please share with me.</p>
  
  <p>Also  what will be happen if I drop these tables?</p>
  
  <p>Some of extra tables' names are given below:</p>
  
  <pre><code>AB,
  AL,
  BCB, 
  BCF, 
  ...
  MD_ADDITIONAL_PROPERTIES, 
  MD_CATALOGS 
  MD_COLUMNS 
  MD_CONNECTIONS
  MD_CONSTRAINT_DETAILS
  MD_CONSTRAINTS 
  MD_DERIVATIVES
  MD_GROUP_MEMBERS 
  MD_GROUP_PRIVILEGES 
  </code></pre>
  
  <p>There are a lot of other tables starting MD_ .</p>