Berkeley DB Reference Guide: Database close

Berkeley DB Reference Guide:
Access Methods

Database close

The DB->close method closes the DB database handle. By default, DB->close also flushes all modified records from the database cache to disk.

There is one flag that you can set to customize DB->close:

DB_NOSYNC

Do not flush cached information to disk.

It is important to understand that flushing cached information to disk only minimizes the window of opportunity for corrupted data, it does not eliminate the possibility.

While unlikely, it is possible for database corruption to happen if a system or application crash occurs while writing data to the database. To ensure that database corruption never occurs, applications must either:

Use transactions and logging with automatic recovery.
Use logging and application-specific recovery.
Edit a copy of the database, and, once all applications using the database have successfully called DB->close, use system operations (for example, the POSIX rename system call) to atomically replace the original database with the updated copy.