<?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>DbLogc::get()</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="lsn.html" title="Chapter 8. The DbLsn Handle" /> <link rel="prev" href="logcclose.html" title="DbLogc::close()" /> <link rel="next" href="logcompare.html" title="DbEnv::log_compare()" /> </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">DbLogc::get()</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="logcclose.html">Prev</a> </td> <th width="60%" align="center">Chapter 8. The DbLsn Handle </th> <td width="20%" align="right"> <a accesskey="n" href="logcompare.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="logcget"></a>DbLogc::get()</h2> </div> </div> </div> <pre class="programlisting">#include <db_cxx.h> int DbLogc::get(DbLsn *lsn, Dbt *data, u_int32_t flags);</pre> <p> The <code class="methodname">DbLogc::get()</code> method returns records from the log. </p> <p> Unless otherwise specified, the <code class="methodname">DbLogc::get()</code> <span> <span> 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. </span> </span> </p> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idp8546272"></a>Parameters</h3> </div> </div> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="idp8545624"></a>lsn</h4> </div> </div> </div> <p> When the <span class="bold"><strong>flag</strong></span> parameter is set to DB_CURRENT, DB_FIRST, DB_LAST, DB_NEXT or DB_PREV, the <span class="bold"><strong>lsn</strong></span> parameter is overwritten with the <a class="link" href="lsn.html" title="Chapter 8. The DbLsn Handle">DbLsn</a> value of the record retrieved. When <span class="bold"><strong>flag</strong></span> is set to DB_SET, the <span class="bold"><strong>lsn</strong></span> parameter is the <a class="link" href="lsn.html" title="Chapter 8. The DbLsn Handle">DbLsn</a> value of the record to be retrieved. </p> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="idp8550328"></a>data</h4> </div> </div> </div> <p> The data field of the <span class="bold"><strong>data</strong></span> structure is set to the record retrieved, and the size field indicates the number of bytes in the record. See <a class="link" href="dbt.html" title="Chapter 4. The Dbt Handle">Dbt</a> for a description of other fields in the <span class="bold"><strong>data</strong></span> structure. The <a class="link" href="dbt.html#dbt_DB_DBT_MALLOC">DB_DBT_MALLOC</a>, <a class="link" href="dbt.html#dbt_DB_DBT_REALLOC">DB_DBT_REALLOC</a> and <a class="link" href="dbt.html#dbt_DB_DBT_USERMEM">DB_DBT_USERMEM</a> flags may be specified for any <a class="link" href="dbt.html" title="Chapter 4. The Dbt Handle">Dbt</a> used for data retrieval. </p> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="idp8539952"></a>flags</h4> </div> </div> </div> <p> The <span class="bold"><strong>flags</strong></span> parameter must be set to one of the following values: </p> <div class="itemizedlist"> <ul type="disc"> <li> <p><a id="get_DB_CURRENT"></a> <code class="literal">DB_CURRENT</code> </p> <p> Return the log record to which the log currently refers. </p> </li> <li> <p><a id="get_DB_FIRST"></a> <code class="literal">DB_FIRST</code> </p> <p> The first record from any of the log files found in the log directory 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 <a class="link" href="lsn.html" title="Chapter 8. The DbLsn Handle">DbLsn</a> of the record returned. </p> <p> The <code class="methodname">DbLogc::get()</code> method will return <a href="../../programmer_reference/program_errorret.html#program_errorret.DB_NOTFOUND" class="olink">DB_NOTFOUND</a> if DB_FIRST is set and the log is empty. </p> </li> <li> <p><a id="get_DB_LAST"></a> <code class="literal">DB_LAST</code> </p> <p> 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 <a class="link" href="lsn.html" title="Chapter 8. The DbLsn Handle">DbLsn</a> of the record returned. </p> <p> The <code class="methodname">DbLogc::get()</code> method will return <a href="../../programmer_reference/program_errorret.html#program_errorret.DB_NOTFOUND" class="olink">DB_NOTFOUND</a> if DB_LAST is set and the log is empty. </p> </li> <li> <p><a id="get_DB_NEXT"></a> <code class="literal">DB_NEXT</code> </p> <p> The current log position is advanced to the next record in the 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 <a class="link" href="lsn.html" title="Chapter 8. The DbLsn Handle">DbLsn</a> of the record returned. </p> <p> If the cursor has not been initialized via DB_FIRST, DB_LAST, DB_SET, DB_NEXT, or DB_PREV, <code class="methodname">DbLogc::get()</code> will return the first record in the log. </p> <p> The <code class="methodname">DbLogc::get()</code> method will return <a href="../../programmer_reference/program_errorret.html#program_errorret.DB_NOTFOUND" class="olink">DB_NOTFOUND</a> if DB_NEXT is set and the last log record has already been returned or the log is empty. </p> </li> <li> <p><a id="get_DB_PREV"></a> <code class="literal">DB_PREV</code> </p> <p> The current log position is advanced to the previous record in the 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 <a class="link" href="lsn.html" title="Chapter 8. The DbLsn Handle">DbLsn</a> of the record returned. </p> <p> If the cursor has not been initialized via DB_FIRST, DB_LAST, DB_SET, DB_NEXT, or DB_PREV, <code class="methodname">DbLogc::get()</code> will return the last record in the log. </p> <p> The <code class="methodname">DbLogc::get()</code> method will return <a href="../../programmer_reference/program_errorret.html#program_errorret.DB_NOTFOUND" class="olink">DB_NOTFOUND</a> if DB_PREV is set and the first log record has already been returned or the log is empty. </p> </li> <li> <p><a id="get_DB_SET"></a> <code class="literal">DB_SET</code> </p> <p> Retrieve the record specified by the <span class="bold"><strong>lsn</strong></span> parameter. </p> </li> </ul> </div> </div> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idp8563672"></a>Errors</h3> </div> </div> </div> <p> The <code class="methodname">DbLogc::get()</code> <span> <span> method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a> exception, encapsulating one of the following non-zero errors, or return one of the following non-zero errors: </span> </span> </p> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="idp8552848"></a>EINVAL</h4> </div> </div> </div> <p> If the DB_CURRENT flag was set and the log cursor has not yet been initialized; the DB_CURRENT, DB_NEXT, or DB_PREV flags were set and the log was opened with the DB_THREAD flag set; the DB_SET flag was set and the specified log sequence number does not appear in the log; or if an invalid flag value or parameter was specified. </p> </div> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idp8567160"></a>Class</h3> </div> </div> </div> <p> <a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a>, <a class="link" href="logc.html" title="The DbLogc Handle">DbLogc</a>, <a class="link" href="lsn.html" title="Chapter 8. The DbLsn Handle">DbLsn</a> </p> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idp8561728"></a>See Also</h3> </div> </div> </div> <p> <a class="xref" href="lsn.html#loglist" title="Logging Subsystem and Related Methods">Logging Subsystem and Related Methods</a> </p> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="logcclose.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="lsn.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="logcompare.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">DbLogc::close() </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> DbEnv::log_compare()</td> </tr> </table> </div> </body> </html>