The memp_fsync function writes all pages associated with the
DB_MPOOLFILE, that were marked as modified using memp_fput
or memp_fset, back to the source file. If any of the modified
pages are also pinned (i.e., currently referenced by this or
another process) memp_fsync will ignore them.
The memp_fsync function returns a non-zero error value on failure, 0 on success, and returns DB_INCOMPLETE if there were pages which were
modified but which memp_fsync was unable to write immediately.
Errors
The memp_fsync function may fail and return a non-zero error for errors specified for other Berkeley DB and C library or system functions.
If a catastrophic error has occurred, the memp_fsync function may fail and return
DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail
in the same way.