#include <db_cxx.h> int DbMpoolFile::set_pgcookie(DBT *pgcookie);
         The DbMpoolFile::set_pgcookie() method specifies a byte string that
         is provided to the functions registered to do input or output
         processing of the file's pages as they are read from or written to,
         the backing filesystem store.  (See the 
         DbEnv::memp_register() 
         documentation for more information.)
    
         The DbMpoolFile::set_pgcookie() method configures a file in the
         cache, not only operations performed using the specified 
         DbMpoolFile  handle.
    
         The DbMpoolFile::set_pgcookie() method may not be called after the
         DbMpoolFile::open() 
         method is called. If the file is already open in the cache when
         DbMpoolFile::open()  is
         called, the information specified to DbMpoolFile::set_pgcookie()
         will replace the existing information.
    
         The DbMpoolFile::set_pgcookie() 
            
            
                method either returns a non-zero error value or throws an
                exception that encapsulates a non-zero error value on
                failure, and returns 0 on success.