1<?xml version="1.0" encoding="UTF-8" standalone="no"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml"> 4 <head> 5 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> 6 <title>DB->truncate()</title> 7 <link rel="stylesheet" href="apiReference.css" type="text/css" /> 8 <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> 9 <link rel="start" href="index.html" title="Berkeley DB C API Reference" /> 10 <link rel="up" href="db.html" title="Chapter��2.�� The DB Handle" /> 11 <link rel="prev" href="dbsync.html" title="DB->sync()" /> 12 <link rel="next" href="dbupgrade.html" title="DB->upgrade()" /> 13 </head> 14 <body> 15 <div class="navheader"> 16 <table width="100%" summary="Navigation header"> 17 <tr> 18 <th colspan="3" align="center">DB->truncate()</th> 19 </tr> 20 <tr> 21 <td width="20%" align="left"><a accesskey="p" href="dbsync.html">Prev</a>��</td> 22 <th width="60%" align="center">Chapter��2.�� 23 The DB Handle 24 </th> 25 <td width="20%" align="right">��<a accesskey="n" href="dbupgrade.html">Next</a></td> 26 </tr> 27 </table> 28 <hr /> 29 </div> 30 <div class="sect1" lang="en" xml:lang="en"> 31 <div class="titlepage"> 32 <div> 33 <div> 34 <h2 class="title" style="clear: both"><a id="dbtruncate"></a>DB->truncate()</h2> 35 </div> 36 </div> 37 </div> 38 <pre class="programlisting">#include <db.h> 39 40int 41DB->truncate(DB *db, 42 DB_TXN *txnid, u_int32_t *countp, u_int32_t flags); </pre> 43 <p> 44 The <code class="methodname">DB->truncate()</code> method empties the database, discarding all 45 records it contains. The number of records discarded from the 46 database is returned in <span class="bold"><strong>countp</strong></span>. 47 </p> 48 <p> 49 When called on a database configured with secondary indices using the 50 <a class="xref" href="dbassociate.html" title="DB->associate()">DB->associate()</a> 51 method, the <code class="methodname">DB->truncate()</code> method truncates the primary database and 52 all secondary indices. A count of the records discarded from the 53 primary database is returned. 54 </p> 55 <p> 56 It is an error to call the <code class="methodname">DB->truncate()</code> method on a database with 57 open cursors. 58 </p> 59 <p> 60 The <code class="methodname">DB->truncate()</code> <span> 61 <span> 62 method returns a non-zero error value on failure and 0 on success. 63 </span> 64 65 </span> 66 </p> 67 <div class="sect2" lang="en" xml:lang="en"> 68 <div class="titlepage"> 69 <div> 70 <div> 71 <h3 class="title"><a id="id1652212"></a>Parameters</h3> 72 </div> 73 </div> 74 </div> 75 <div class="sect3" lang="en" xml:lang="en"> 76 <div class="titlepage"> 77 <div> 78 <div> 79 <h4 class="title"><a id="id1652217"></a>countp</h4> 80 </div> 81 </div> 82 </div> 83 <p> 84 The <span class="bold"><strong>countp</strong></span> parameter references 85 memory into which the number of records discarded from the database 86 is copied. 87 </p> 88 </div> 89 <div class="sect3" lang="en" xml:lang="en"> 90 <div class="titlepage"> 91 <div> 92 <div> 93 <h4 class="title"><a id="id1652330"></a>flags</h4> 94 </div> 95 </div> 96 </div> 97 <p> 98 The <span class="bold"><strong>flags</strong></span> parameter is currently 99 unused, and must be set to 0. 100 </p> 101 </div> 102 <div class="sect3" lang="en" xml:lang="en"> 103 <div class="titlepage"> 104 <div> 105 <div> 106 <h4 class="title"><a id="id1652344"></a>txnid</h4> 107 </div> 108 </div> 109 </div> 110 <p> 111 If the operation is part of an application-specified transaction, the 112 <span class="bold"><strong>txnid</strong></span> parameter is a transaction 113 handle returned from <a class="xref" href="txnbegin.html" title="DB_ENV->txn_begin()">DB_ENV->txn_begin()</a>; if the 114 operation is part of a Berkeley DB Concurrent Data Store group, the 115 <span class="bold"><strong>txnid</strong></span> parameter is a handle returned 116 from <a class="xref" href="envcdsgroup_begin.html" title="DB_ENV->cdsgroup_begin()">DB_ENV->cdsgroup_begin()</a>; 117 otherwise NULL. If no transaction handle is specified, but the 118 operation occurs in a transactional database, the operation will be 119 implicitly transaction protected. 120 </p> 121 </div> 122 </div> 123 <div class="sect2" lang="en" xml:lang="en"> 124 <div class="titlepage"> 125 <div> 126 <div> 127 <h3 class="title"><a id="id1652232"></a>Errors</h3> 128 </div> 129 </div> 130 </div> 131 <p> 132 The <code class="methodname">DB->truncate()</code> <span> 133 <span> 134 method may fail and return one of the following non-zero errors: 135 </span> 136 137 </span> 138 </p> 139 <div class="sect3" lang="en" xml:lang="en"> 140 <div class="titlepage"> 141 <div> 142 <div> 143 <h4 class="title"><a id="id1652368"></a>DB_LOCK_DEADLOCK</h4> 144 </div> 145 </div> 146 </div> 147 <p> 148 A transactional database environment operation was selected to resolve 149 a deadlock. 150 </p> 151 </div> 152 <div class="sect3" lang="en" xml:lang="en"> 153 <div class="titlepage"> 154 <div> 155 <div> 156 <h4 class="title"><a id="id1652229"></a>DB_LOCK_NOTGRANTED</h4> 157 </div> 158 </div> 159 </div> 160 <p> 161 A Berkeley DB Concurrent Data Store database environment configured 162 for lock timeouts was unable to grant a lock in the allowed time. 163 </p> 164 </div> 165 <div class="sect3" lang="en" xml:lang="en"> 166 <div class="titlepage"> 167 <div> 168 <div> 169 <h4 class="title"><a id="id1652399"></a>EINVAL</h4> 170 </div> 171 </div> 172 </div> 173 <p> 174 If there are open cursors in the database; or if an invalid flag value or parameter was specified. 175 </p> 176 </div> 177 </div> 178 <div class="sect2" lang="en" xml:lang="en"> 179 <div class="titlepage"> 180 <div> 181 <div> 182 <h3 class="title"><a id="id1652315"></a>Class</h3> 183 </div> 184 </div> 185 </div> 186 <p> 187 <a class="link" href="db.html" title="Chapter��2.�� The DB Handle">DB</a> 188 </p> 189 </div> 190 <div class="sect2" lang="en" xml:lang="en"> 191 <div class="titlepage"> 192 <div> 193 <div> 194 <h3 class="title"><a id="id1652381"></a>See Also</h3> 195 </div> 196 </div> 197 </div> 198 <p> 199 <a class="xref" href="db.html#dblist" title="Database and Related Methods">Database and Related Methods</a> 200 </p> 201 </div> 202 </div> 203 <div class="navfooter"> 204 <hr /> 205 <table width="100%" summary="Navigation footer"> 206 <tr> 207 <td width="40%" align="left"><a accesskey="p" href="dbsync.html">Prev</a>��</td> 208 <td width="20%" align="center"> 209 <a accesskey="u" href="db.html">Up</a> 210 </td> 211 <td width="40%" align="right">��<a accesskey="n" href="dbupgrade.html">Next</a></td> 212 </tr> 213 <tr> 214 <td width="40%" align="left" valign="top">DB->sync()��</td> 215 <td width="20%" align="center"> 216 <a accesskey="h" href="index.html">Home</a> 217 </td> 218 <td width="40%" align="right" valign="top">��DB->upgrade()</td> 219 </tr> 220 </table> 221 </div> 222 </body> 223</html> 224