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13<b>DbEnv::cdsgroup_begin</b>
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21<b><pre>
22#include &lt;db_cxx.h&gt;
23<p>
24int
25DbEnv::cdsgroup_begin(DbTxn **tid);
26</pre></b>
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28<b>Description: DbEnv::cdsgroup_begin</b>
29<a name="2"><!--meow--></a>
30<p>The DbEnv::cdsgroup_begin method allocates a locker ID in an
31environment configured for Berkeley DB Concurrent Data Store applications.  It copies a pointer to
32a <a href="../api_cxx/txn_class.html">DbTxn</a> that uniquely identifies the locker ID into the memory
33to which <b>tid</b> refers.  Calling the <a href="../api_cxx/txn_commit.html">DbTxn::commit</a> method will
34discard the allocated locker ID.</p>
35<p>See <a href="../ref/cam/intro.html">Berkeley DB Concurrent Data Store applications</a> for more
36information about when this is required.</p>
37<p>The DbEnv::cdsgroup_begin method may be called at any time during the life of the
38application.</p>
39<p>The DbEnv::cdsgroup_begin method
40either returns a non-zero error value
41or throws an exception that encapsulates a non-zero error value on
42failure, and returns 0 on success.
43</p>
44<br><b>Errors</b>
45<p>If the maximum number of lockers has been reached, the DbEnv::cdsgroup_begin method will fail and
46either return ENOMEM or
47throw a DbMemoryException.</p>
48<hr size=1 noshade>
49<br><b>Class</b>
50<a href="../api_cxx/env_class.html">DbEnv</a>, <a href="../api_cxx/txn_class.html">DbTxn</a>
51<br><b>See Also</b>
52<a href="../api_cxx/txn_list.html">Transaction Subsystem and Related Methods</a>
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