env txn
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env txn
[-nosync]
[-nowait]
[-parent txnid]
[-sync]
Description(env txn)
The env txn command begins a transaction. The returned transaction
handle is bound to a Tcl command of the form env.txnX, where
X is an integer starting at 0 (for example, env0.txn0 and env0.txn1).
It is through this Tcl command that the script accesses the transaction
methods.
The options are as follows:
- -nosync
- Do not synchronously flush the log when this transaction commits or
prepares. This means the transaction will exhibit the ACI (atomicity,
consistency, and isolation) properties, but not D (durability); that
is, database integrity will be maintained, but it is possible that this
transaction may be undone during recovery instead of being redone.
This behavior may be set for an entire Berkeley DB environment as part of the
berkdb env call.
- -nowait
- If a lock is unavailable for any Berkeley DB operation performed in the context
of this transaction, throw a Tcl error immediately instead of blocking on
the lock.
- -parent txnid
- Create the new transaction as a nested transaction, with the specified
transaction indicated as its parent. Transactions may be nested to any
level.
- -sync
- Synchronously flush the log when this transaction commits or prepares.
This means the transaction will exhibit all of the ACID (atomicity,
consistency, isolation, and durability) properties.
This behavior is the default for Berkeley DB environments unless the
-nosync option was specified to the berkdb env call.
The env txn command returns a transaction handle on success.
In the case of error, a Tcl error is thrown.
Copyright (c) 1996-2005 Sleepycat Software, Inc. - All rights reserved.