error(package(db, deadlock), _)
This exception indicates a deadlock was raised by one of the DB predicates. Deadlocks may arise if multiple processes or threads access the same keys in a different order. The DB infra-structure causes one of the processes involved in the deadlock to abort its transaction. This process may choose to restart the transaction.
For example, a DB application may define {Goal}
to
realise transactions and restart these automatically is a deadlock is
raised:
{Goal} :- catch(bdb_transaction(Goal), E, true), ( var(E) -> true ; E = error(package(db, deadlock), _) -> {Goal} ; throw(E) ).
Environment | defines the environment to which the transaction applies. If omitted, the default environment is used. See bdb_init/1 and bdb_init/2. |