#include <db.h> int DB_MPOOLFILE->get_fileid(DB_MPOOLFILE *mpf, u_int8_t *fileid);
         The DB_MPOOLFILE->get_fileid() method copies the
         file's identifier into the memory location referenced by fileid. The fileid specifies a unique
         identifier for the file, which is used so that the cache functions
         (that is, the shared memory buffer pool functions) are able to
         uniquely identify files. This is necessary for multiple processes
         wanting to share a file to correctly identify the file in the
         cache.
    
         The DB_MPOOLFILE->get_fileid() 
            
                  method returns a non-zero error value on failure and 0 on success.