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<p>For the Queue and Recno access methods, when the <a href="../api_reference/C/dbput.html#dbput_DB_APPEND" class="olink">DB_APPEND</a> flag
is specified to the <a href="../api_reference/C/dbput.html" class="olink">DB->put()</a> method, the allocated record number is
returned to the application in the <span class="bold"><strong>key</strong></span> <a href="../api_reference/C/dbt.html" class="olink">DBT</a> argument. In
previous releases of Berkeley DB, this <a href="../api_reference/C/dbt.html" class="olink">DBT</a> structure did not follow
the usual <a href="../api_reference/C/dbt.html" class="olink">DBT</a> conventions. For example, it was not possible to
cause Berkeley DB to allocate space for the returned record number. Rather,
it was always assumed that the <span class="bold"><strong>data</strong></span> field of the <span class="bold"><strong>key</strong></span>
structure referred to memory that could be used as storage for a
db_recno_t type.</p>
<p>As of the Berkeley DB 3.1.0 release, the <span class="bold"><strong>key</strong></span> structure behaves as
described in the <a href="../api_reference/C/dbt.html" class="olink">DBT</a> C++/Java class or C structure documentation.</p>
<p>Applications which are using the <a href="../api_reference/C/dbput.html#dbput_DB_APPEND" class="olink">DB_APPEND</a> flag for Queue and
Recno access method databases will require a change to upgrade to the
Berkeley DB 3.1 releases. The simplest change is likely to be to add the
<a href="../api_reference/C/dbt.html#dbt_DB_DBT_USERMEM" class="olink">DB_DBT_USERMEM</a> flag to the <span class="bold"><strong>key</strong></span> structure. For example,
code that appears as follows:</p>
<pre class="programlisting">DBT key;
db_recno_t recno;
memset(&key, 0, sizeof(DBT));
key.data = &recno;
key.size = sizeof(recno);
DB->put(DB, NULL, &key, &data, DB_APPEND);
printf("new record number is %lu\n", (u_long)recno);</pre>
<p>would be changed to:</p>
<pre class="programlisting">DBT key;
db_recno_t recno;
memset(&key, 0, sizeof(DBT));
key.data = &recno;
key.ulen = sizeof(recno);
key.flags = DB_DBT_USERMEM;
DB->put(DB, NULL, &key, &data, DB_APPEND);
printf("new record number is %lu\n", (u_long)recno);</pre>
<p>Note that the <span class="bold"><strong>ulen</strong></span> field is now set as well as the flag value.
An alternative change would be:</p>
<pre class="programlisting">DBT key;
db_recno_t recno;
memset(&key, 0, sizeof(DBT));
DB->put(DB, NULL, &key, &data, DB_APPEND);
recno = *(db_recno_t *)key->data;
printf("new record number is %lu\n", (u_long)recno);</pre>
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