#include <DbXml.hpp> XmlTransaction XmlTransaction::createChild(u_int32_t flags = 0)
The XmlTransaction::createChild method
creates a child transaction of this transaction. While this child
transaction is active (has been neither committed nor aborted), the
parent transaction may not issue any operations except for
XmlTransaction::commit or XmlTransaction::abort.
This parameter must be set to 0 or by bitwise inclusively OR'ing together one or more of the following values:
This operation will have degree 2 isolation. This provides for cursor stability but not repeatable reads. Data items which have been previously read by this transaction may be deleted or modified by other transactions before this transaction completes.
This operation will support degree 1 isolation; that is,
read operations may return data that has been modified
by other transactions but which has not yet been
committed. Silently ignored if the DB_READ_UNCOMMITTED
flag was not specified when the underlying container was
opened.
Do not synchronously flush the log when this transaction commits or prepares. This means the transaction will exhibit the ACI (atomic, consistent, and isolated) properties, but not D (durable); that is, database integrity will be maintained but it is possible that this transaction may be undone during recovery.
This behavior may be set for a Berkeley DB environment
using the DbEnv::set_flags() method. Any value
specified to this method overrides that setting.
DBXML_IGNORE_LEASE
This flag is relevant only when using a replicated environment.
Perform transactional operations irrespective of the state of master leases. The transactional operations will perform under all conditions: if master leases are not configured, if the request is made to a client, if the request is made to a master with a valid lease, or if the request is made to a master without a valid lease.
Refer to Master Leases in the Berkeley DB Programmer's Reference Guide for more information.
If a lock is unavailable for any Berkeley DB operation
performed in the context of this transaction, cause the
operation to return DB_LOCK_DEADLOCK or throw an
XmlException
with DB error code DB_LOCK_DEADLOCK
immediately instead of blocking on the lock.
This transaction will execute with snapshot isolation.
For containers with the DB_MULTIVERSION flag set, data
values will be read as they are when the transaction
begins, without taking read locks. Silently ignored for
operations on databases with DB_MULTIVERSION not set on
the underlying container (read locks are acquired).
The DB_LOCK_DEADLOCK error is returned from update
operations if a snapshot transaction attempts to update
data which was modified after the snapshot transaction
read it.
Synchronously flush the log when this transaction commits or prepares. This means the transaction will exhibit all of the ACID (atomic, consistent, isolated, and durable) properties.
This behavior is the default for Berkeley DB
environments unless the DB_TXN_NOSYNC flag was
specified to the DbEnv::set_flags() method. Any
value specified to this method overrides that setting.