<?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>DbMultipleKeyDataBuilder</title> <link rel="stylesheet" href="apiReference.css" type="text/css" /> <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> <link rel="start" href="index.html" title="Berkeley DB C++ API Reference" /> <link rel="up" href="dbt.html" title="Chapter 4. The Dbt Handle" /> <link rel="prev" href="dbmultipledatabuilder.html" title="DbMultipleDataBuilder" /> <link rel="next" href="dbmultiplerecnodatabuilder.html" title="DbMultipleRecnoDataBuilder" /> </head> <body> <div xmlns="" class="navheader"> <div class="libver"> <p>Library Version 11.2.5.3</p> </div> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">DbMultipleKeyDataBuilder</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="dbmultipledatabuilder.html">Prev</a> </td> <th width="60%" align="center">Chapter 4. The Dbt Handle </th> <td width="20%" align="right"> <a accesskey="n" href="dbmultiplerecnodatabuilder.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="dbmultiplekeydatabuilder"></a>DbMultipleKeyDataBuilder</h2> </div> </div> </div> <pre class="programlisting">#include <db_cxx.h> class DbMultipleKeyDataBuilder { public: DbMultipleKeyDataBuilder(Dbt &dbt); bool append(void *kbuf, size_t klen, void *dbuf, size_t dlen); bool reserve(void *&kdest, size_t klen, void *&ddest, size_t dlen); }; </pre> <p> This class builds a bulk buffer for use when the <a class="link" href="dbput.html#put_DB_MULTIPLE_KEY">DB_MULTIPLE_KEY</a> flag is specified to either the <a class="xref" href="dbput.html" title="Db::put()">Db::put()</a> or <a class="xref" href="dbdel.html" title="Db::del()">Db::del()</a> methods with the btree or hash access methods. The buffer in the <a class="link" href="dbt.html" title="Chapter 4. The Dbt Handle">Dbt</a> passed to the constructor is filled by calls to <a class="xref" href="dbmultiplekeydatabuilder.html#dbmultiplekeydatabuilder.append" title="DbMultipleKeyDataBuilder.append()">DbMultipleKeyDataBuilder.append()</a> or <a class="xref" href="dbmultiplekeydatabuilder.html#dbmultiplekeydatabuilder.reserve" title="DbMultipleKeyDataBuilder.reserve()">DbMultipleKeyDataBuilder.reserve()</a>. </p> <p> The constructor takes a <a class="xref" href="dbt.html" title="Chapter 4. The Dbt Handle"> The Dbt Handle </a> that must be configured to contain a buffer managed by the application, with the <code class="literal">ulen</code> field set to the size of the buffer. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <h3 class="title">Note</h3> <p> All instances of the bulk retrieval classes may be used only once, and to build the bulk buffer in the forward direction only. </p> </div> <p> Parameters are: </p> <div class="itemizedlist"> <ul type="disc"> <li> <p> <code class="literal">dbt</code> </p> <p> The <span class="bold"><strong>dbt</strong></span> parameter is a <a class="xref" href="dbt.html" title="Chapter 4. The Dbt Handle"> The Dbt Handle </a> that must already be configured to contain a buffer managed by the application, with the <code class="literal">ulen</code> field set to the size of the buffer, which must be a multiple of 4. </p> </li> </ul> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="dbmultiplekeydatabuilder.append"></a>DbMultipleKeyDataBuilder.append()</h3> </div> </div> </div> <p> The <code class="methodname">DbMultipleKeyDataBuilder.append()</code> method copies a key/data pair to the end of the buffer. </p> <p> The <code class="methodname">DbMultipleKeyDataBuilder.append()</code> method returns <code class="literal">false</code> if the key/data pair does not fit in the buffer and <code class="literal">true</code> otherwise. </p> <p> Parameters are: </p> <div class="itemizedlist"> <ul type="disc"> <li> <p> <code class="literal">kbuf</code> </p> <p> A pointer to the key to be copied into the bulk buffer. </p> </li> <li> <p> <code class="literal">klen</code> </p> <p> The number of bytes of the key to be copied. </p> </li> <li> <p> <code class="literal">dbuf</code> </p> <p> A pointer to the data item to be copied into the bulk buffer. </p> </li> <li> <p> <code class="literal">dlen</code> </p> <p> The number of bytes of the data item to be copied. </p> </li> </ul> </div> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="dbmultiplekeydatabuilder.reserve"></a>DbMultipleKeyDataBuilder.reserve()</h3> </div> </div> </div> <p> The <code class="methodname">DbMultipleKeyDataBuilder.reserve()</code> method reserves space for the next key/data pair in the bulk buffer. Unlike the <code class="methodname">append()</code>, no data is actually copied into the bulk buffer by <code class="methodname">reserve()</code>: copying the data is the responsibility of the application. </p> <p> The <code class="methodname">DbMultipleKeyDataBuilder.reserve()</code> method returns <code class="literal">false</code> if the data does not fit in the buffer and <code class="literal">true</code> otherwise. </p> <p> Parameters are: </p> <div class="itemizedlist"> <ul type="disc"> <li> <p> <code class="literal">kdest</code> </p> <p> Set to a pointer to the position in the bulk buffer reserved for the key, if enough space is available. </p> </li> <li> <p> <code class="literal">klen</code> </p> <p> The number of bytes to reserve for the key. </p> </li> <li> <p> <code class="literal">ddest</code> </p> <p> Set to a pointer to the position in the bulk buffer reserved for the data item, if enough space is available. </p> </li> <li> <p> <code class="literal">dlen</code> </p> <p> The number of bytes to reserve for the data item. </p> </li> </ul> </div> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idp6533640"></a>Class</h3> </div> </div> </div> <p> <a class="link" href="dbmultiplebuilder.html" title="DbMultipleBuilder">DbMultipleBuilder</a> </p> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idp6540368"></a>See Also</h3> </div> </div> </div> <p> <a class="xref" href="dbt.html#dbtlist" title="DBT and Bulk Operations">DBT and Bulk Operations</a> </p> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="dbmultipledatabuilder.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="dbt.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="dbmultiplerecnodatabuilder.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">DbMultipleDataBuilder </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> DbMultipleRecnoDataBuilder</td> </tr> </table> </div> </body> </html>