<!--$Id: db_set_append_recno.so,v 1.24 2006/05/17 20:47:46 bostic Exp $--> <!--Copyright (c) 1997,2007 Oracle. All rights reserved.--> <!--See the file LICENSE for redistribution information.--> <html> <head> <title>Berkeley DB: Db::set_append_recno</title> <meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> <meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> </head> <body bgcolor=white> <table width="100%"><tr valign=top> <td> <h3>Db::set_append_recno</h3> </td> <td align=right> <a href="../../db46-devel-4.6.21/api_cxx/api_core.html"><img src="../../db46-devel-4.6.21/images/api.gif" alt="API"></a> <a href="../../db46-devel-4.6.21/ref/toc.html"><img src="../../db46-devel-4.6.21/images/ref.gif" alt="Ref"></a></td> </tr></table> <hr size=1 noshade> <tt> <h3><pre> #include <db_cxx.h> <p> int Db::set_append_recno(int (*db_append_recno_fcn)(DB *dbp, Dbt *data, db_recno_t recno)); </pre></h3> <hr size=1 noshade> <h3>Description: Db::set_append_recno</h3> <p>When using the <a href="../../db46-devel-4.6.21/api_cxx/db_put.html#DB_APPEND">DB_APPEND</a> option of the <a href="../../db46-devel-4.6.21/api_cxx/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.</p> <p>The Db::set_append_recno method configures operations performed using the specified <a href="../../db46-devel-4.6.21/api_cxx/db_class.html">Db</a> handle, not all operations performed on the underlying database.</p> <p>The Db::set_append_recno method may not be called after the <a href="../../db46-devel-4.6.21/api_cxx/db_open.html">Db::open</a> method is called. </p> <p>The Db::set_append_recno method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success. </p> <h3>Parameters</h3> <dl compact> <dt><b>db_append_recno_fcn</b><dd>The <b>db_append_recno_fcn</b> parameter is a function to call after the record number has been selected but before the data has been stored into the database. The function takes three parameters: <dl compact> <dt><b>db</b><dd>The <b>db</b> parameter is the enclosing database handle. <dt><b>dbt</b><dd>The <b>dbt</b> parameter is the data <a href="../../db46-devel-4.6.21/api_cxx/dbt_class.html">Dbt</a> to be stored. <dt><b>recno</b><dd>The <b>recno</b> parameter is the generated record number. </dl> <p>The called function may modify the data <a href="../../db46-devel-4.6.21/api_cxx/dbt_class.html">Dbt</a>. If the function needs to allocate memory for the <b>data</b> field, the <b>flags</b> field of the returned <a href="../../db46-devel-4.6.21/api_cxx/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> <p>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> <p>Berkeley DB is not re-entrant. Callback functions should not attempt to make library calls (for example, to release locks or close open handles). Re-entering Berkeley DB is not guaranteed to work correctly, and the results are undefined.</p> </dl> <h3>Errors</h3> <p>The Db::set_append_recno method may fail and throw <a href="../../db46-devel-4.6.21/api_cxx/except_class.html">DbException</a>, encapsulating one of the following non-zero errors, or return one of the following non-zero errors:</p> <dl compact> <dt>EINVAL<dd>If the method was called after <a href="../../db46-devel-4.6.21/api_cxx/db_open.html">Db::open</a> was called; or if an invalid flag value or parameter was specified. </dl> <hr size=1 noshade> <h3>Class</h3> <a href="../../db46-devel-4.6.21/api_cxx/db_class.html">Db</a> <h3>See Also</h3> <a href="../../db46-devel-4.6.21/api_cxx/db_list.html">Databases and Related Methods</a> </tt> <table width="100%"><tr><td><br></td><td align=right> <a href="../../db46-devel-4.6.21/api_cxx/api_core.html"><img src="../../db46-devel-4.6.21/images/api.gif" alt="API"></a><a href="../../db46-devel-4.6.21/ref/toc.html"><img src="../../db46-devel-4.6.21/images/ref.gif" alt="Ref"></a> </td></tr></table> <p><font size=1>Copyright (c) 1996,2007 Oracle. All rights reserved.</font> </body> </html>