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<!--Id: logc_get.so,v 10.36 2002/07/01 16:52:26 bostic Exp -->
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<title>Berkeley DB: DB_LOGC->get</title>
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<h1>DB_LOGC->get</h1>
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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>
<h1>Description</h1>
<p>The DB_LOGC->get function retrieve records from the log according to the
<b>lsn</b> and <b>flags</b> arguments.
<p>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.html">DBT</a> for a description of other fields in the
<b>data</b> structure. The <a href="../api_c/dbt.html#DB_DBT_MALLOC">DB_DBT_MALLOC</a>,
<a href="../api_c/dbt.html#DB_DBT_REALLOC">DB_DBT_REALLOC</a> and <a href="../api_c/dbt.html#DB_DBT_USERMEM">DB_DBT_USERMEM</a> flags may be specified
for any <a href="../api_c/dbt.html">DBT</a> used for data retrieval.
<p>The <b>flags</b> value must be set to one of the following values:
<p><dl compact>
<p><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> argument.
The <b>lsn</b> argument is overwritten with the <a href="../api_c/db_lsn.html">DB_LSN</a> of the
record returned.
<p>
If the log is empty, the DB_LOGC->get function will return DB_NOTFOUND.
<p><dt><a name="DB_LAST">DB_LAST</a><dd>The last record in the log is returned in the <b>data</b> argument.
The <b>lsn</b> argument is overwritten with the <a href="../api_c/db_lsn.html">DB_LSN</a> of the
record returned.
<p>
If the log is empty, the DB_LOGC->get function will return DB_NOTFOUND.
<p><dt><a name="DB_NEXT">DB_NEXT</a>, <a name="DB_PREV">DB_PREV</a><dd>The current log position is advanced to the next (previous) record in
the log, and that record is returned in the <b>data</b> argument. The
<b>lsn</b> argument is overwritten with the <a href="../api_c/db_lsn.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 (last) record
in the log.
If the last (first) log record has already been returned or the log is
empty, the DB_LOGC->get function will return DB_NOTFOUND.
If the log was opened with the DB_THREAD flag set, calls to
DB_LOGC->get with the DB_NEXT (DB_PREV) flag set, the DB_LOGC->get function will return EINVAL.
<p><dt><a name="DB_CURRENT">DB_CURRENT</a><dd>Return the log record to which the log currently refers.
If the log cursor has not been initialized via DB_FIRST, DB_LAST,
DB_SET, DB_NEXT, or DB_PREV, or if the log was opened with the DB_THREAD
flag set, the DB_LOGC->get function will return EINVAL.
<p><dt><a name="DB_SET">DB_SET</a><dd>Retrieve the record specified by the <b>lsn</b> argument.
If the specified <a href="../api_c/db_lsn.html">DB_LSN</a> is invalid (for example, it does not
appear in the log), the DB_LOGC->get function will return EINVAL.
</dl>
<p>
Otherwise, the DB_LOGC->get function returns a non-zero error value on failure and 0 on success.
<h1>Errors</h1>
<p>The DB_LOGC->get function may fail and return a non-zero error for the following conditions:
<p><dl compact>
<p><dt>EINVAL<dd>An invalid flag value or parameter was specified.
<p>The DB_CURRENT flag was set and the log pointer had not yet been
initialized.
<p>The DB_SET flag was set and the specified log sequence number does not
exist.
</dl>
<p>The DB_LOGC->get function may fail and return a non-zero error for errors specified for other Berkeley DB and C library or system functions.
If a catastrophic error has occurred, the DB_LOGC->get function may fail and
return <a href="../ref/program/errorret.html#DB_RUNRECOVERY">DB_RUNRECOVERY</a>,
in which case all subsequent Berkeley DB calls will fail in the same way.
<h1>See Also</h1>
<a href="../api_c/log_archive.html">DB_ENV->log_archive</a>,
<a href="../api_c/log_file.html">DB_ENV->log_file</a>,
<a href="../api_c/log_flush.html">DB_ENV->log_flush</a>,
<a href="../api_c/log_put.html">DB_ENV->log_put</a>,
<a href="../api_c/log_stat.html">DB_ENV->log_stat</a>,
<a href="../api_c/env_set_lg_bsize.html">DB_ENV->set_lg_bsize</a>,
<a href="../api_c/env_set_lg_dir.html">DB_ENV->set_lg_dir</a>,
<a href="../api_c/env_set_lg_max.html">DB_ENV->set_lg_max</a>,
<a href="../api_c/env_set_lg_regionmax.html">DB_ENV->set_lg_regionmax</a>,
and
<a href="../api_c/log_compare.html">log_compare</a>.
<p>
<a href="../api_c/log_cursor.html">DB_ENV->log_cursor</a>,
<a href="../api_c/logc_close.html">DB_LOGC->close</a>
and
<a href="../api_c/logc_get.html">DB_LOGC->get</a>.
</tt>
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