/usr/lib/swipl/library/persistency.pl
AllApplicationManualNameSummaryHelp

 db_attach(:File, +Options)
Use File as persistent database for the calling module. The calling module must defined persistent/1 to declare the database terms. Defined options:
sync(+Sync)
One of close (close journal after write), flush (default, flush journal after write) or none (handle as fully buffered stream).

If File is already attached this operation may change the sync behaviour.