code: public Catalog loadSchema(HSQLInterface hsql,
                                DdlProceduresToLoad whichProcs,
                                String... ddlFilePaths) throws VoltCompilerException
      {
          m_catalog = new Catalog(); //
          m_catalog.execute("add / clusters cluster");
          Database db = initCatalogDatabase(m_catalog);
          List<VoltCompilerReader> ddlReaderList = DDLPathsToReaderList(ddlFilePaths);
          final VoltDDLElementTracker voltDdlTracker = new VoltDDLElementTracker(this);
          InMemoryJarfile jarOutput = new InMemoryJarfile();
          compileDatabase(db, hsql, voltDdlTracker, null, null, ddlReaderList, null, whichProcs, jarOutput);
  
          return m_catalog;
      }
docs: Simplified interface for loading a ddl file with full support for VoltDB
  extensions (partitioning, procedures, export), but no support for "project file" input.
  This is, at least initially, only a back door to create a fully functional catalog for
  the purposes of planner unit testing.
  @param hsql an interface to the hsql frontend, initialized and potentially reused by the caller.
  @param whichProcs indicates which ddl-defined procedures to load: none, single-statement, or all
  @param ddlFilePaths schema file paths
  @throws VoltCompilerException