public TableDataIO_Indexed(TableDefinition def) throws Exception {
   super(def);
   indexFile = BaseIO.getFile(def.getTableName() + "_" + def.getPK() + ".idx");
 }
 protected boolean indexExists(String colname) {
   return new File(
           BaseIO.getInitDir() + File.separator + def.getTableName() + "_" + colname + ".idx")
       .exists();
 }