To enable sharing of databases between process, programs have to create environments and the databases should be opened in these environments. A database can be shared between processes that open it in the same environment. An environment physically consists of a directory containing the files needed to enable sharing databases between processes. The directory of the environment has to be located in a local file system.
Databases can be opened outside any environment (see
db_open/4), but in that case a process writing the database
must ensure exclusive access or the behavior of the predicates is