title: Is it feasible to perform a cross database federated query in redshift?
body: <p>while cross database queries (in ra3 node based clusters) and federated queries individually seem to work, together it seems that they won't work. I am most probably missing something, hence the question. Below are the details:</p>
  <ul>
  <li>RDS Aurora MySQL has a database say DB1</li>
  <li>Redshift cluster say c1 has databases say RSDB1 and RSDB2</li>
  <li>I am able to configure DB1 as external schema in RSDB1 say ext_mdb and able to query as well ex: as below</li>
  </ul>
  <blockquote>
  <p>select count(1) from ext_mdb.Table2;</p>
  </blockquote>
  <blockquote>
  <p>select count(1) from RSDB1.ext_mdb.Table2; # this also works</p>
  </blockquote>
  <ul>
  <li>I am also able to use the cross databases query schema RSDB1.public.Table1  while I am connected to RSDB2.</li>
  <li>When I try querying RSDB1.ext_mdb.Table2 from RSDB2 fails with below error</li>
  </ul>
  <blockquote>
  <p>select count(1) from RSDB1.ext_mdb.Table2; # this doesn't from RSDB2</p>
  </blockquote>
  <blockquote>
  <p>ERROR:  Relation Table2 does not exist in the database.</p>
  </blockquote>