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<h1>DB->set_append_recno</h1>
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<h3><pre>
#include <db.h>
<p>
int
DB->set_append_recno(DB *,
int (*db_append_recno_fcn)(DB *dbp, DBT *data, db_recno_t recno));
</pre></h3>
<h1>Description</h1>
<p>When using the <a href="../api_c/db_put.html#DB_APPEND">DB_APPEND</a> option of the <a href="../api_c/db_put.html">DB->put</a> method,
it may be useful to modify the stored data based on the generated key.
If a callback function is specified using the
DB->set_append_recno method, it will be called after the record number
has been selected, but before the data has been stored.
The callback function must return 0 on success and <b>errno</b> or
a value outside of the Berkeley DB error name space on failure.
<p>The called function must take three arguments: a reference to the
enclosing database handle; the data <a href="../api_c/dbt_class.html">DBT</a> to be stored; and the
selected record number. The called function may then modify the data
<a href="../api_c/dbt_class.html">DBT</a>.
<p>If the callback function needs to allocate memory for the <b>data</b>
field, the <b>flags</b> field of the returned <a href="../api_c/dbt_class.html">DBT</a> should be
set to DB_DBT_APPMALLOC, which indicates that Berkeley DB should free
the memory when it is done with it.
<p>The DB->set_append_recno method configures operations performed using the specified
<a href="../api_c/db_class.html">DB</a> handle, not all operations performed on the underlying
database.
<p>The DB->set_append_recno interface may not be called after the <a href="../api_c/db_open.html">DB->open</a>
interface is called.
<p>The DB->set_append_recno method returns a non-zero error value on failure and 0 on success.
<h1>Class</h1>
<a href="../api_c/db_class.html">DB</a>
<h1>See Also</h1>
<a href="../api_c/db_list.html">Databases and Related Methods</a>
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