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<h2 class="title" style="clear: both"><a id="txn_commit"></a><span class="emphasis"><em>txn</em></span> commit</h2>
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<pre class="programlisting">txn commit
[-nosync]
[-sync] </pre>
<p>
The <span class="emphasis"><em>txn</em></span> <span class="bold"><strong>commit</strong></span>
command ends the transaction.
</p>
<p>
In the case of nested transactions, if the transaction is a parent
transaction with unresolved (neither committed or aborted) child
transactions, the child transactions are aborted and the commit of the
parent will succeed.
</p>
<p>
In the case of nested transactions, if the transaction is a child
transaction, its locks are not released, but are acquired by its
parent. Although the commit of the child transaction will succeed, the
actual resolution of the child transaction is postponed until the
parent transaction is committed or aborted; that is, if its parent
transaction commits, it will be committed, and if its parent
transaction aborts, it will be aborted.
</p>
<p>
If the <span class="bold"><strong>-nosync</strong></span> option is not
specified, a commit log record is written and flushed to disk, as are
all previously written log records.
</p>
<p>
The options are as follows:
</p>
<div class="itemizedlist">
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<li>
<p>
<span class="bold"><strong>-nosync</strong></span>
</p>
<p>
Do not synchronously flush the log. 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.
</p>
<p>
This behavior may be set for an entire Berkeley DB environment as part
of the <span class="bold"><strong>berkdb env</strong></span> call.
</p>
</li>
<li>
<p>
<span class="bold"><strong>-sync</strong></span>
</p>
<p>
Synchronously flush the log. This means the transaction will exhibit
all of the ACID (atomicity, consistency, isolation and durability)
properties.
</p>
<p>
This behavior is the default for Berkeley DB environments unless the
<span class="bold"><strong>-nosync</strong></span> option was specified to the
<span class="bold"><strong>berkdb env</strong></span> or
<span class="emphasis"><em>env</em></span> <span class="bold"><strong>txn</strong></span> calls.
</p>
</li>
</ul>
</div>
<p>
After <span class="emphasis"><em>txn</em></span> <span class="bold"><strong>commit</strong></span>
has been called, regardless of its return, the <span class="bold"><strong>txn</strong></span> handle may not be accessed again. If
<span class="emphasis"><em>txn</em></span> <span class="bold"><strong>commit</strong></span>
encounters an error, this transaction and all child transactions of
this transaction are aborted.
</p>
<p>
The <span class="emphasis"><em>txn</em></span> <span class="bold"><strong>commit</strong></span>
command returns 0 on success, and in the case of error, a Tcl error is
thrown.
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