1<!--$Id: logc_get.so,v 10.48 2004/08/13 03:38:57 bostic Exp $--> 2<!--Copyright (c) 1997,2008 Oracle. All rights reserved.--> 3<!--See the file LICENSE for redistribution information.--> 4<html> 5<head> 6<title>Berkeley DB: DB_LOGC->get</title> 7<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> 8<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> 9</head> 10<body bgcolor=white> 11<table width="100%"><tr valign=top> 12<td> 13<b>DB_LOGC->get</b> 14</td> 15<td align=right> 16<a href="../api_c/api_core.html"><img src="../images/api.gif" alt="API"></a> 17<a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a></td> 18</tr></table> 19<hr size=1 noshade> 20<tt> 21<b><pre> 22#include <db.h> 23<p> 24int 25DB_LOGC->get(DB_LOGC *logc, DB_LSN *lsn, DBT *data, u_int32_t flags); 26</pre></b> 27<hr size=1 noshade> 28<b>Description: DB_LOGC->get</b> 29<p>The DB_LOGC->get method returns records from the log.</p> 30<p>Unless otherwise specified, the DB_LOGC->get method 31returns a non-zero error value on failure 32and 0 on success. 33</p> 34<b>Parameters</b> <br> 35 <b>data</b><ul compact><li>The data field of the <b>data</b> structure is set to the record 36retrieved, and the size field indicates the number of bytes in the 37record. See <a href="../api_c/dbt_class.html">DBT</a> for a description of other fields in the 38<b>data</b> structure. The <a href="../api_c/dbt_class.html#DB_DBT_MALLOC">DB_DBT_MALLOC</a>, 39<a href="../api_c/dbt_class.html#DB_DBT_REALLOC">DB_DBT_REALLOC</a> and <a href="../api_c/dbt_class.html#DB_DBT_USERMEM">DB_DBT_USERMEM</a> flags may be specified 40for any <a href="../api_c/dbt_class.html">DBT</a> used for data retrieval.</ul> 41 <b>flags</b><ul compact><li>The <b>flags</b> parameter must be set to one of the following values: 42<br> 43<b><a name="DB_CURRENT">DB_CURRENT</a></b><ul compact><li>Return the log record to which the log currently refers.</ul> 44<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 45is returned in the <b>data</b> parameter. 46The <b>lsn</b> parameter is overwritten with the <a href="../api_c/lsn_class.html">DB_LSN</a> of the 47record returned. 48<p>The DB_LOGC->get method will return <a href="../ref/program/errorret.html#DB_NOTFOUND">DB_NOTFOUND</a> if DB_FIRST is set and the log is empty. 49</p></ul> 50<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. 51The <b>lsn</b> parameter is overwritten with the <a href="../api_c/lsn_class.html">DB_LSN</a> of the 52record returned. 53<p>The DB_LOGC->get method will return <a href="../ref/program/errorret.html#DB_NOTFOUND">DB_NOTFOUND</a> if DB_LAST is set and the log is empty. 54</p></ul> 55<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 56that record is returned in the <b>data</b> parameter. The <b>lsn</b> 57parameter is overwritten with the <a href="../api_c/lsn_class.html">DB_LSN</a> of the record returned. 58<p>If the cursor has not been initialized via DB_FIRST, DB_LAST, DB_SET, 59DB_NEXT, or DB_PREV, DB_LOGC->get will return the first record in 60the log.</p> 61<p>The DB_LOGC->get method will return <a href="../ref/program/errorret.html#DB_NOTFOUND">DB_NOTFOUND</a> if DB_NEXT is set and the last log record has already been 62returned or the log is empty. 63</p></ul> 64<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, 65and that record is returned in the <b>data</b> parameter. The 66<b>lsn</b> parameter is overwritten with the <a href="../api_c/lsn_class.html">DB_LSN</a> of the record 67returned. 68<p>If the cursor has not been initialized via DB_FIRST, DB_LAST, DB_SET, 69DB_NEXT, or DB_PREV, DB_LOGC->get will return the last record in the 70log.</p> 71<p>The DB_LOGC->get method will return <a href="../ref/program/errorret.html#DB_NOTFOUND">DB_NOTFOUND</a> if DB_PREV is set and the first log record has already been 72returned or the log is empty. 73</p></ul> 74<b><a name="DB_SET">DB_SET</a></b><ul compact><li>Retrieve the record specified by the <b>lsn</b> parameter.</ul> 75<br></ul> 76 <b>lsn</b><ul compact><li>When the <b>flag</b> parameter is set to DB_CURRENT, 77DB_FIRST, DB_LAST, DB_NEXT or DB_PREV, 78the <b>lsn</b> parameter is overwritten with the <a href="../api_c/lsn_class.html">DB_LSN</a> value 79of the record retrieved. When <b>flag</b> is set to DB_SET, 80the <b>lsn</b> parameter is the <a href="../api_c/lsn_class.html">DB_LSN</a> value of the record to 81be retrieved.</ul> 82<br> 83<br><b>Errors</b> 84<p>The DB_LOGC->get method 85may fail and return one of the following non-zero errors:</p> 86<br> 87<b>EINVAL</b><ul compact><li>If the DB_CURRENT flag was set and the log cursor has not yet 88been initialized; 89the DB_CURRENT, DB_NEXT, or DB_PREV flags were 90set and the log was opened with the DB_THREAD flag set; 91the DB_SET flag was set and the specified log sequence number 92does not appear in the log; or if an 93invalid flag value or parameter was specified.</ul> 94<br> 95<hr size=1 noshade> 96<br><b>Class</b> 97<a href="../api_c/env_class.html">DB_ENV</a>, <a href="../api_c/logc_class.html">DB_LOGC</a>, <a href="../api_c/lsn_class.html">DB_LSN</a> 98<br><b>See Also</b> 99<a href="../api_c/log_list.html">Logging Subsystem and Related Methods</a> 100</tt> 101<table width="100%"><tr><td><br></td><td align=right> 102<a href="../api_c/api_core.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a> 103</td></tr></table> 104<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> 105</body> 106</html> 107
