int DB->sync(DB *db, u_int32_t flags);
The DB->sync method flushes any cached information to disk.
If the database is in memory only, the DB->sync method has no effect and will always succeed.
The flags parameter is currently unused, and must be set to 0.
It is important to understand that flushing cached information to disk only minimizes the window of opportunity for corrupted data. Although 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; or edit a copy of the database, and once all applications using the database have successfully called DB->close, atomically replace the original database with the updated copy.
The DB->sync method returns a non-zero error value on failure and 0 on success.
The DB->sync method may fail and return a non-zero error for the following conditions:
The DB->sync method may fail and return a non-zero error for errors specified for other Berkeley DB and C library or system functions. If a catastrophic error has occurred, the DB->sync method may fail and return DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.
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