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<!--$Id: logc_get.so,v 10.48 2004/08/13 03:38:57 bostic Exp $--> <!--Copyright (c) 1997,2008 Oracle. All rights reserved.--> <!--See the file LICENSE for redistribution information.--> <html> <head> <title>Berkeley DB: DbLogc::get</title> <meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> <meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> </head> <body bgcolor=white> <table width="100%"><tr valign=top> <td> <b>DbLogc::get</b> </td> <td align=right> <a href="../../db4-devel-4.7.25/api_cxx/api_core.html"><img src="../../db4-devel-4.7.25/images/api.gif" alt="API"></a> <a href="../../db4-devel-4.7.25/ref/toc.html"><img src="../../db4-devel-4.7.25/images/ref.gif" alt="Ref"></a></td> </tr></table> <hr size=1 noshade> <tt> <b><pre> #include <db_cxx.h> <p> int DbLogc::get(DbLsn *lsn, Dbt *data, u_int32_t flags); </pre></b> <hr size=1 noshade> <b>Description: DbLogc::get</b> <p>The DbLogc::get method returns records from the log.</p> <p>Unless otherwise specified, the DbLogc::get 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. </p> <b>Parameters</b> <br> <b>data</b><ul compact><li>The data field of the <b>data</b> structure is set to the record retrieved, and the size field indicates the number of bytes in the record. See <a href="../../db4-devel-4.7.25/api_cxx/dbt_class.html">Dbt</a> for a description of other fields in the <b>data</b> structure. The <a href="../../db4-devel-4.7.25/api_cxx/dbt_class.html#DB_DBT_MALLOC">DB_DBT_MALLOC</a>, <a href="../../db4-devel-4.7.25/api_cxx/dbt_class.html#DB_DBT_REALLOC">DB_DBT_REALLOC</a> and <a href="../../db4-devel-4.7.25/api_cxx/dbt_class.html#DB_DBT_USERMEM">DB_DBT_USERMEM</a> flags may be specified for any <a href="../../db4-devel-4.7.25/api_cxx/dbt_class.html">Dbt</a> used for data retrieval.</ul> <b>flags</b><ul compact><li>The <b>flags</b> parameter must be set to one of the following values: <br> <b><a name="DB_CURRENT">DB_CURRENT</a></b><ul compact><li>Return the log record to which the log currently refers.</ul> <b><a name="DB_FIRST">DB_FIRST</a></b><ul compact><li>The first record from any of the log files found in the log directory is returned in the <b>data</b> parameter. The <b>lsn</b> parameter is overwritten with the <a href="../../db4-devel-4.7.25/api_cxx/lsn_class.html">DbLsn</a> of the record returned. <p>The DbLogc::get method will return <a href="../../db4-devel-4.7.25/ref/program/errorret.html#DB_NOTFOUND">DB_NOTFOUND</a> if DB_FIRST is set and the log is empty. </p></ul> <b><a name="DB_LAST">DB_LAST</a></b><ul compact><li>The last record in the log is returned in the <b>data</b> parameter. The <b>lsn</b> parameter is overwritten with the <a href="../../db4-devel-4.7.25/api_cxx/lsn_class.html">DbLsn</a> of the record returned. <p>The DbLogc::get method will return <a href="../../db4-devel-4.7.25/ref/program/errorret.html#DB_NOTFOUND">DB_NOTFOUND</a> if DB_LAST is set and the log is empty. </p></ul> <b><a name="DB_NEXT">DB_NEXT</a></b><ul compact><li>The current log position is advanced to the next record in the log, and that record is returned in the <b>data</b> parameter. The <b>lsn</b> parameter is overwritten with the <a href="../../db4-devel-4.7.25/api_cxx/lsn_class.html">DbLsn</a> of the record returned. <p>If the cursor has not been initialized via DB_FIRST, DB_LAST, DB_SET, DB_NEXT, or DB_PREV, DbLogc::get will return the first record in the log.</p> <p>The DbLogc::get method will return <a href="../../db4-devel-4.7.25/ref/program/errorret.html#DB_NOTFOUND">DB_NOTFOUND</a> if DB_NEXT is set and the last log record has already been returned or the log is empty. </p></ul> <b><a name="DB_PREV">DB_PREV</a></b><ul compact><li>The current log position is advanced to the previous record in the log, and that record is returned in the <b>data</b> parameter. The <b>lsn</b> parameter is overwritten with the <a href="../../db4-devel-4.7.25/api_cxx/lsn_class.html">DbLsn</a> of the record returned. <p>If the cursor has not been initialized via DB_FIRST, DB_LAST, DB_SET, DB_NEXT, or DB_PREV, DbLogc::get will return the last record in the log.</p> <p>The DbLogc::get method will return <a href="../../db4-devel-4.7.25/ref/program/errorret.html#DB_NOTFOUND">DB_NOTFOUND</a> if DB_PREV is set and the first log record has already been returned or the log is empty. </p></ul> <b><a name="DB_SET">DB_SET</a></b><ul compact><li>Retrieve the record specified by the <b>lsn</b> parameter.</ul> <br></ul> <b>lsn</b><ul compact><li>When the <b>flag</b> parameter is set to DB_CURRENT, DB_FIRST, DB_LAST, DB_NEXT or DB_PREV, the <b>lsn</b> parameter is overwritten with the <a href="../../db4-devel-4.7.25/api_cxx/lsn_class.html">DbLsn</a> value of the record retrieved. When <b>flag</b> is set to DB_SET, the <b>lsn</b> parameter is the <a href="../../db4-devel-4.7.25/api_cxx/lsn_class.html">DbLsn</a> value of the record to be retrieved.</ul> <br> <br><b>Errors</b> <p>The DbLogc::get method may fail and throw <a href="../../db4-devel-4.7.25/api_cxx/except_class.html">DbException</a>, encapsulating one of the following non-zero errors, or return one of the following non-zero errors:</p> <br> <b>EINVAL</b><ul compact><li>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.</ul> <br> <hr size=1 noshade> <br><b>Class</b> <a href="../../db4-devel-4.7.25/api_cxx/env_class.html">DbEnv</a>, <a href="../../db4-devel-4.7.25/api_cxx/logc_class.html">DbLogc</a>, <a href="../../db4-devel-4.7.25/api_cxx/lsn_class.html">DbLsn</a> <br><b>See Also</b> <a href="../../db4-devel-4.7.25/api_cxx/log_list.html">Logging Subsystem and Related Methods</a> </tt> <table width="100%"><tr><td><br></td><td align=right> <a href="../../db4-devel-4.7.25/api_cxx/api_core.html"><img src="../../db4-devel-4.7.25/images/api.gif" alt="API"></a><a href="../../db4-devel-4.7.25/ref/toc.html"><img src="../../db4-devel-4.7.25/images/ref.gif" alt="Ref"></a> </td></tr></table> <p><font size=1>Copyright (c) 1996,2008 Oracle. 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