:- use_module(library(semweb/rdf_persistency)). rdf_persistency(+DB, 
+Bool)
rdf_persistency(+DB, 
+Bool)false, the 
journal and snapshot for the database are deleted and further changes to 
triples associated with DB are not recorded. If Bool 
is true a snapshot is created for the current state and 
further modifications are monitored. Switching persistency does not 
affect the triples in the in-memory RDF database.