<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>Release 3.1: DB->put</title> <link rel="stylesheet" href="gettingStarted.css" type="text/css" /> <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> <link rel="start" href="index.html" title="Berkeley DB Programmer's Reference Guide" /> <link rel="up" href="upgrade_3_1_toc.html" title="Chapter 34. Upgrading Berkeley DB 3.0 applications to Berkeley DB 3.1" /> <link rel="prev" href="upgrade_3_1_set_paniccall.html" title="Release 3.1: DB_ENV->set_paniccall, DB->set_paniccall" /> <link rel="next" href="upgrade_3_1_dup.html" title="Release 3.1: identical duplicate data items" /> </head> <body> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">Release 3.1: DB->put</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="upgrade_3_1_set_paniccall.html">Prev</a> </td> <th width="60%" align="center">Chapter 34. Upgrading Berkeley DB 3.0 applications to Berkeley DB 3.1</th> <td width="20%" align="right"> <a accesskey="n" href="upgrade_3_1_dup.html">Next</a></td> </tr> </table> <hr /> </div> <div class="sect1" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h2 class="title" style="clear: both"><a id="upgrade_3_1_put"></a>Release 3.1: DB->put</h2> </div> </div> </div> <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> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="upgrade_3_1_set_paniccall.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="upgrade_3_1_toc.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="upgrade_3_1_dup.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">Release 3.1: DB_ENV->set_paniccall, DB->set_paniccall </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> Release 3.1: identical duplicate data items</td> </tr> </table> </div> </body> </html>