Db::truncate()

#include <db_cxx.h>
 
int
Db::truncate(DbTxn *txnid, u_int32_t *countp, u_int32_t flags);

The Db::truncate() method empties the database, discarding all records it contains. The number of records discarded from the database is returned in countp.

When called on a database configured with secondary indices using the Db::associate() method, the Db::truncate() method truncates the primary database and all secondary indices. A count of the records discarded from the primary database is returned.

It is an error to call the Db::truncate() method on a database with open cursors.

The Db::truncate() method is non-atomic when used on a sliced database. If the operation fails, it is possible for the resulting database files to be in an inconsistent state.

The Db::truncate() 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.

Parameters

txnid

If the operation is part of an application-specified transaction, the txnid parameter is a transaction handle returned from DbEnv::txn_begin() ; if the operation is part of a Berkeley DB Concurrent Data Store group, the txnid parameter is a handle returned from DbEnv::cdsgroup_begin() ; otherwise NULL. If no transaction handle is specified, but the operation occurs in a transactional database, the operation will be implicitly transaction protected.

countp

The countp parameter references memory into which the number of records discarded from the database is copied.

flags

The flags parameter is currently unused, and must be set to 0.

Errors

The Db::truncate() 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:

DbDeadlockException or DB_LOCK_DEADLOCK

A transactional database environment operation was selected to resolve a deadlock.

DbDeadlockException is thrown if your Berkeley DB API is configured to throw exceptions. Otherwise, DB_LOCK_DEADLOCK is returned.

DbLockNotGrantedException or DB_LOCK_NOTGRANTED

A Berkeley DB Concurrent Data Store database environment configured for lock timeouts was unable to grant a lock in the allowed time.

You attempted to open a database handle that is configured for no waiting exclusive locking, but the exclusive lock could not be immediately obtained. See Db::set_lk_exclusive() for more information.

DbLockNotGrantedException is thrown if your Berkeley DB API is configured to throw exceptions. Otherwise, DB_LOCK_NOTGRANTED is returned.

EINVAL

If there are open cursors in the database; or if an invalid flag value or parameter was specified.

Class

Db

See Also

Database and Related Methods