#include <db_cxx.h> int Db::sync(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.
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 either returns a non-zero error value or throws an
exception that encapsulates a non-zero error value on
failure, and returns 0 on success.
The Db::sync()
method may fail and throw a DbException
exception, encapsulating one of the following non-zero errors, or return one
of the following non-zero errors:
When a client synchronizes with the master, it is possible for committed
transactions to be rolled back. This invalidates all the database and cursor
handles opened in the replication environment. Once this occurs, an attempt to use
such a handle will
throw a DbRepHandleDeadException (if
your application is configured to throw exceptions), or
return DB_REP_HANDLE_DEAD.
The application will need to discard the handle and open a new one in order to
continue processing.
The operation was blocked by client/master synchronization.
DbDeadlockException is thrown if
your Berkeley DB API is configured to throw exceptions.
Otherwise, DB_REP_LOCKOUT is returned.