code: public void planSwapTables() {
          // reset any error message
          m_recentErrorMsg = null;
  
          // Reset plan node ids to start at 1 for this plan
          AbstractPlanNode.resetPlanNodeIds();
  
          assert(m_sql.startsWith("@SwapTables "));
          String[] swapTableArgs = m_sql.split(" ");
          m_xmlSQL = forgeVoltXMLForSwapTables(
                  swapTableArgs[1], swapTableArgs[2]);
          m_planSelector.outputCompiledStatement(m_xmlSQL);
      }
docs: Fast track the parsing for the pseudo-statement generated by the
  {@literal @}SwapTables system stored procedure.
  <p>
  If this functionality turns out to fall within the behavior of a
  more general SWAP TABLE statement supported in a (future) SQL
  parser, the system stored procedure can fall back to using it.
  Extending the HSQL parser NOW to support a "SWAP TABLE" statement
  JUST for this special case, but keeping that support disabled for
  the normal {@literal @}AdHoc and compiled stored procedures code paths would
  be overkill at this point.
  So we settle for this early return of a "forged" parser result.
  <p>
  Note that we don't allow this from an {@literal @}AdHoc compilation.  See
  ENG-12368.