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_LOGC->get()</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="lsn.html" title="Chapter��7.�� The DB_LSN Handle" /> 11 <link rel="prev" href="logcclose.html" title="DB_LOGC->close()" /> 12 <link rel="next" href="logcompare.html" title="log_compare" /> 13 </head> 14 <body> 15 <div class="navheader"> 16 <table width="100%" summary="Navigation header"> 17 <tr> 18 <th colspan="3" align="center">DB_LOGC->get()</th> 19 </tr> 20 <tr> 21 <td width="20%" align="left"><a accesskey="p" href="logcclose.html">Prev</a>��</td> 22 <th width="60%" align="center">Chapter��7.�� 23 The DB_LSN Handle 24 </th> 25 <td width="20%" align="right">��<a accesskey="n" href="logcompare.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="logcget"></a>DB_LOGC->get()</h2> 35 </div> 36 </div> 37 </div> 38 <pre class="programlisting">#include <db.h> 39 40int 41DB_LOGC->get(DB_LOGC *logc, DB_LSN *lsn, DBT *data, u_int32_t flags); </pre> 42 <p> 43 The <code class="methodname">DB_LOGC->get()</code> method returns records from the log. 44 </p> 45 <p> 46 Unless otherwise specified, the <code class="methodname">DB_LOGC->get()</code> <span> 47 <span> 48 method returns a non-zero error value on failure and 0 on success. 49 </span> 50 51 </span> 52 </p> 53 <div class="sect2" lang="en" xml:lang="en"> 54 <div class="titlepage"> 55 <div> 56 <div> 57 <h3 class="title"><a id="id1684585"></a>Parameters</h3> 58 </div> 59 </div> 60 </div> 61 <div class="sect3" lang="en" xml:lang="en"> 62 <div class="titlepage"> 63 <div> 64 <div> 65 <h4 class="title"><a id="id1684594"></a>data</h4> 66 </div> 67 </div> 68 </div> 69 <p> 70 The data field of the <span class="bold"><strong>data</strong></span> structure 71 is set to the record retrieved, and the size field indicates the 72 number of bytes in the record. See 73 <a class="link" href="dbt.html" title="Chapter��4.�� The DBT Handle">DBT</a> for a description of other 74 fields in the <span class="bold"><strong>data</strong></span> structure. The 75 <a class="link" href="dbt.html#dbt_DB_DBT_MALLOC">DB_DBT_MALLOC</a>, 76 <a class="link" href="dbt.html#dbt_DB_DBT_REALLOC">DB_DBT_REALLOC</a> 77 and <a class="link" href="dbt.html#dbt_DB_DBT_USERMEM">DB_DBT_USERMEM</a> 78 flags may be specified for any 79 <a class="link" href="dbt.html" title="Chapter��4.�� The DBT Handle">DBT</a> used for data retrieval. 80 </p> 81 </div> 82 <div class="sect3" lang="en" xml:lang="en"> 83 <div class="titlepage"> 84 <div> 85 <div> 86 <h4 class="title"><a id="id1684847"></a>flags</h4> 87 </div> 88 </div> 89 </div> 90 <p> 91 The <span class="bold"><strong>flags</strong></span> parameter must be set to 92 one of the following values: 93 </p> 94 <div class="itemizedlist"> 95 <ul type="disc"> 96 <li> 97 <p><a id="get_DB_CURRENT"></a> 98 <code class="literal">DB_CURRENT</code> 99 </p> 100 <p> 101 Return the log record to which the log currently refers. 102 </p> 103 </li> 104 <li> 105 <p><a id="get_DB_FIRST"></a> 106 <code class="literal">DB_FIRST</code> 107 </p> 108 <p> 109 The first record from any of the log files found in the log directory 110 is returned in the <span class="bold"><strong>data</strong></span> parameter. 111 The <span class="bold"><strong>lsn</strong></span> parameter is overwritten with 112 the <a class="link" href="lsn.html" title="Chapter��7.�� The DB_LSN Handle">DB_LSN</a> of the record 113 returned. 114 </p> 115 <p> 116 The <code class="methodname">DB_LOGC->get()</code> method will return <a href="../../programmer_reference/program_errorret.html#program_errorret.DB_NOTFOUND" class="olink">DB_NOTFOUND</a> if 117 DB_FIRST is set and the log is empty. 118 </p> 119 </li> 120 <li> 121 <p><a id="get_DB_LAST"></a> 122 <code class="literal">DB_LAST</code> 123 </p> 124 <p> 125 The last record in the log is returned in the <span class="bold"><strong>data</strong></span> parameter. The <span class="bold"><strong>lsn</strong></span> parameter is overwritten with the 126 <a class="link" href="lsn.html" title="Chapter��7.�� The DB_LSN Handle">DB_LSN</a> of the record returned. 127 </p> 128 <p> 129 The <code class="methodname">DB_LOGC->get()</code> method will return <a href="../../programmer_reference/program_errorret.html#program_errorret.DB_NOTFOUND" class="olink">DB_NOTFOUND</a> if 130 DB_LAST is set and the log is empty. 131 </p> 132 </li> 133 <li> 134 <p><a id="get_DB_NEXT"></a> 135 <code class="literal">DB_NEXT</code> 136 </p> 137 <p> 138 The current log position is advanced to the next record in the log, 139 and that record is returned in the <span class="bold"><strong>data</strong></span> parameter. The <span class="bold"><strong>lsn</strong></span> parameter is overwritten with the 140 <a class="link" href="lsn.html" title="Chapter��7.�� The DB_LSN Handle">DB_LSN</a> of the record returned. 141 </p> 142 <p> 143 If the cursor has not been initialized via DB_FIRST, DB_LAST, DB_SET, 144 DB_NEXT, or DB_PREV, <code class="methodname">DB_LOGC->get()</code> will return the first record in 145 the log. 146 </p> 147 <p> 148 The <code class="methodname">DB_LOGC->get()</code> method will return <a href="../../programmer_reference/program_errorret.html#program_errorret.DB_NOTFOUND" class="olink">DB_NOTFOUND</a> if 149 DB_NEXT is set and the last log record has already been returned or 150 the log is empty. 151 </p> 152 </li> 153 <li> 154 <p><a id="get_DB_PREV"></a> 155 <code class="literal">DB_PREV</code> 156 </p> 157 <p> 158 The current log position is advanced to the previous record in the 159 log, and that record is returned in the <span class="bold"><strong>data</strong></span> parameter. The <span class="bold"><strong>lsn</strong></span> parameter is overwritten with the 160 <a class="link" href="lsn.html" title="Chapter��7.�� The DB_LSN Handle">DB_LSN</a> of the record returned. 161 </p> 162 <p> 163 If the cursor has not been initialized via DB_FIRST, DB_LAST, DB_SET, 164 DB_NEXT, or DB_PREV, <code class="methodname">DB_LOGC->get()</code> will return the last record in 165 the log. 166 </p> 167 <p> 168 The <code class="methodname">DB_LOGC->get()</code> method will return <a href="../../programmer_reference/program_errorret.html#program_errorret.DB_NOTFOUND" class="olink">DB_NOTFOUND</a> if 169 DB_PREV is set and the first log record has already been returned or 170 the log is empty. 171 </p> 172 </li> 173 <li> 174 <p><a id="get_DB_SET"></a> 175 <code class="literal">DB_SET</code> 176 </p> 177 <p> 178 Retrieve the record specified by the <span class="bold"><strong>lsn</strong></span> parameter. 179 </p> 180 </li> 181 </ul> 182 </div> 183 </div> 184 <div class="sect3" lang="en" xml:lang="en"> 185 <div class="titlepage"> 186 <div> 187 <div> 188 <h4 class="title"><a id="id1684586"></a>lsn</h4> 189 </div> 190 </div> 191 </div> 192 <p> 193 When the <span class="bold"><strong>flag</strong></span> parameter is set to 194 DB_CURRENT, DB_FIRST, DB_LAST, DB_NEXT or DB_PREV, the <span class="bold"><strong>lsn</strong></span> parameter is overwritten with the 195 <a class="link" href="lsn.html" title="Chapter��7.�� The DB_LSN Handle">DB_LSN</a> value of the record 196 retrieved. When <span class="bold"><strong>flag</strong></span> is set to 197 DB_SET, the <span class="bold"><strong>lsn</strong></span> parameter is the 198 <a class="link" href="lsn.html" title="Chapter��7.�� The DB_LSN Handle">DB_LSN</a> value of the 199 record to be retrieved. 200 </p> 201 </div> 202 </div> 203 <div class="sect2" lang="en" xml:lang="en"> 204 <div class="titlepage"> 205 <div> 206 <div> 207 <h3 class="title"><a id="id1685133"></a>Errors</h3> 208 </div> 209 </div> 210 </div> 211 <p> 212 The <code class="methodname">DB_LOGC->get()</code> <span> 213 <span> 214 method may fail and return one of the following non-zero errors: 215 </span> 216 217 </span> 218 </p> 219 <div class="sect3" lang="en" xml:lang="en"> 220 <div class="titlepage"> 221 <div> 222 <div> 223 <h4 class="title"><a id="id1684924"></a>EINVAL</h4> 224 </div> 225 </div> 226 </div> 227 <p> 228 If the DB_CURRENT flag was set and the log cursor has not yet been 229 initialized; the DB_CURRENT, DB_NEXT, or DB_PREV flags were set and 230 the log was opened with the DB_THREAD flag set; the DB_SET flag was 231 set and the specified log sequence number does not appear in the log; 232 or if an invalid flag value or parameter was specified. 233 </p> 234 </div> 235 </div> 236 <div class="sect2" lang="en" xml:lang="en"> 237 <div class="titlepage"> 238 <div> 239 <div> 240 <h3 class="title"><a id="id1685105"></a>Class</h3> 241 </div> 242 </div> 243 </div> 244 <p> 245 <a class="link" href="env.html" title="Chapter��5.�� The DB_ENV Handle">DB_ENV</a>, 246 <a class="link" href="logc.html" title="The DB_LOGC Handle">DB_LOGC</a>, 247 <a class="link" href="lsn.html" title="Chapter��7.�� The DB_LSN Handle">DB_LSN</a> 248 </p> 249 </div> 250 <div class="sect2" lang="en" xml:lang="en"> 251 <div class="titlepage"> 252 <div> 253 <div> 254 <h3 class="title"><a id="id1684767"></a>See Also</h3> 255 </div> 256 </div> 257 </div> 258 <p> 259 <a class="xref" href="lsn.html#loglist" title="Logging Subsystem and Related Methods">Logging Subsystem and Related Methods</a> 260 </p> 261 </div> 262 </div> 263 <div class="navfooter"> 264 <hr /> 265 <table width="100%" summary="Navigation footer"> 266 <tr> 267 <td width="40%" align="left"><a accesskey="p" href="logcclose.html">Prev</a>��</td> 268 <td width="20%" align="center"> 269 <a accesskey="u" href="lsn.html">Up</a> 270 </td> 271 <td width="40%" align="right">��<a accesskey="n" href="logcompare.html">Next</a></td> 272 </tr> 273 <tr> 274 <td width="40%" align="left" valign="top">DB_LOGC->close()��</td> 275 <td width="20%" align="center"> 276 <a accesskey="h" href="index.html">Home</a> 277 </td> 278 <td width="40%" align="right" valign="top">��log_compare</td> 279 </tr> 280 </table> 281 </div> 282 </body> 283</html> 284