Since the database format of a Berkeley DB may change from version to
version it may become necessary to migrate a database when upgrading.
To this purpose there are two predicates available:
(see The Predicates).
The export/import feature was introduced in SICStus 3.12.0, but in
that version you have to use
bdb:import/[2,3]. Neither is exported from the bdb
module, but can be used with module prefixing.
Since the bdb interface uses a custom hash function (see Berkeley DB), the standard Berkeley DB migration tools will not work.