Library Version 18.1.40

Db::truncate()
Prev | Chapter 2. The Db Handle | Next

## 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

Prev | Up | Next
Db::sync() | Home | Db::upgrade()