The native Prolog database is not very well suited for either very
large data-sets or dynamically changing large data-sets that need to be
communicated between Prolog instances or need to be safely guarded
against system failure. These cases ask for an external database that
can be attached quickly and provides protection against system failure.
The Berkeley DB package is an open source library realising the
bottom-layers of a database. It is a modular system, which in it's
simplest deals with resource management on a mapped file and in its most
complex form deals with network transparency, transaction management,
locking, recovery, life-backup, etc.
The DB library maps keys to values. Optionally multiple values can be
associated with a key. Both key and value are arbitrary-length binary
objects.
This package stores arbitrary Prolog terms into the database,
serializing them using PL_record_external(). This provides an
interface similar to the recorded-database (recorda/3),
which supports terms with internal sharing, cycles and attributes. In
addition, it can store restricted data types such as atoms, strings and
integers using standard representations which allows for sharing the
database with other languages.
This manual is by no means complete. The Berkeley DB documentation
should be consulted directly to resolve details on security, resource
usage, formats, configuration options etc. This interface passed default
values for most DB API calls. Supported options hint to the
corresponding DB API calls, which should be consulted for details.
