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<h2 class="title" style="clear: both"><a id="txnset_commit_token"></a>DB_TXN->set_commit_token()</h2>
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<pre class="programlisting">#include <db.h>
int
DB_TXN->set_commit_token(DB_TXN *txn, DB_TXN_TOKEN *buffer); </pre>
<p>
The <code class="methodname">DB_TXN->set_commit_token()</code> method
configures the transaction for commit token generation, and accepts
the address of an application-supplied buffer to receive the token.
The actual generation of the token contents does not occur until
commit time.
</p>
<p>
Commit tokens are used to enable some consistency guarantees for
replicated applications. Please see the
<a href="../../programmer_reference/rep_ryw.html" class="olink">Read your writes consistency</a>
section in the <em class="citetitle">Berkeley DB Programmer's Reference Guide</em>
for more information.
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<p>
The <code class="methodname">DB_TXN->set_commit_token()</code> method may be
called at any time after the
<a class="xref" href="txnbegin.html" title="DB_ENV->txn_begin()">DB_ENV->txn_begin()</a>
method has been called, and before
<a class="xref" href="txncommit.html" title="DB_TXN->commit()">DB_TXN->commit()</a>
has been called.
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<p>
The <code class="methodname">DB_TXN->set_commit_token()</code> <span>
<span>
method returns a non-zero error value on failure and 0 on success.
</span>
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<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
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<h3 class="title"><a id="id3706130"></a>Parameters</h3>
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<div class="sect3" lang="en" xml:lang="en">
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<h4 class="title"><a id="id3706235"></a>buffer</h4>
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<p>
The address of an application-supplied buffer.
The buffer memory must remain available, and will
be filled in later by Berkeley DB, at the time of
the commit() call.
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<h3 class="title"><a id="id3706241"></a>Errors</h3>
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<p>
The <code class="methodname">DB_TXN->set_commit_token()</code> <span>
<span>
method may fail and return one of the following non-zero errors:
</span>
</span>
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<h4 class="title"><a id="id3704360"></a>EINVAL</h4>
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<p>
If the transaction is a nested transaction; if
this method is called on a replication client;
if the database environment is not configured
for logging.
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<h3 class="title"><a id="id3705714"></a>Class</h3>
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<p>
<a class="link" href="txn.html" title="Chapter 12. The DB_TXN Handle">DB_TXN</a>
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<h3 class="title"><a id="id3706307"></a>See Also</h3>
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<p>
<a class="xref" href="txn.html#txnlist" title="Transaction Subsystem and Related Methods">Transaction Subsystem and Related Methods</a>,
<a class="xref" href="rep.html#replist" title="Replication and Related Methods">Replication and Related Methods</a>
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