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<!--$Id: logc_get.so,v 10.48 2004/08/13 03:38:57 bostic Exp $-->
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<title>Berkeley DB: DB_LOGC->get</title>
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<h3>DB_LOGC->get</h3>
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<h3><pre>
#include <db.h>
<p>
int
DB_LOGC->get(DB_LOGC *logc, DB_LSN *lsn, DBT *data, u_int32_t flags);
</pre></h3>
<hr size=1 noshade>
<h3>Description: DB_LOGC->get</h3>
<p>The DB_LOGC->get method returns records from the log.</p>
<p>Unless otherwise specified, the DB_LOGC->get method
returns a non-zero error value on failure
and 0 on success.
</p>
<h3>Parameters</h3>
<dl compact>
<dt><b>data</b><dd>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="../api_c/dbt_class.html">DBT</a> for a description of other fields in the
<b>data</b> structure. The <a href="../api_c/dbt_class.html#DB_DBT_MALLOC">DB_DBT_MALLOC</a>,
<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
for any <a href="../api_c/dbt_class.html">DBT</a> used for data retrieval.
<dt><b>flags</b><dd>The <b>flags</b> parameter must be set to one of the following values:
<dl compact>
<dt><a name="DB_CURRENT">DB_CURRENT</a><dd>Return the log record to which the log currently refers.
<dt><a name="DB_FIRST">DB_FIRST</a><dd>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="../api_c/lsn_class.html">DB_LSN</a> of the
record returned.
<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.
</p>
<dt><a name="DB_LAST">DB_LAST</a><dd>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="../api_c/lsn_class.html">DB_LSN</a> of the
record returned.
<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.
</p>
<dt><a name="DB_NEXT">DB_NEXT</a><dd>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="../api_c/lsn_class.html">DB_LSN</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, DB_LOGC->get will return the first record in
the log.</p>
<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
returned or the log is empty.
</p>
<dt><a name="DB_PREV">DB_PREV</a><dd>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="../api_c/lsn_class.html">DB_LSN</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, DB_LOGC->get will return the last record in the
log.</p>
<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
returned or the log is empty.
</p>
<dt><a name="DB_SET">DB_SET</a><dd>Retrieve the record specified by the <b>lsn</b> parameter.
</dl>
<dt><b>lsn</b><dd>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="../api_c/lsn_class.html">DB_LSN</a> value
of the record retrieved. When <b>flag</b> is set to DB_SET,
the <b>lsn</b> parameter is the <a href="../api_c/lsn_class.html">DB_LSN</a> value of the record to
be retrieved.
</dl>
<h3>Errors</h3>
<p>The DB_LOGC->get method
may fail and return one of the following non-zero errors:</p>
<dl compact>
<dt>EINVAL<dd>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.
</dl>
<hr size=1 noshade>
<h3>Class</h3>
<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>
<h3>See Also</h3>
<a href="../api_c/log_list.html">Logging Subsystem and Related Methods</a>
</tt>
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