#include <db_cxx.h> int DbMpoolFile::get_fileid(u_int8_t *fileid);
         The DbMpoolFile::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 DbMpoolFile::get_fileid() 
            
            
                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.