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<h2 class="title" style="clear: both"><a id="envset_lg_max"></a>DbEnv::set_lg_max()</h2>
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<pre class="programlisting">#include <db_cxx.h>
int
DbEnv::set_lg_max(u_int32_t lg_max); </pre>
<p>
Set the maximum size of a single file in the log, in bytes. Because
<a class="link" href="lsn.html" title="Chapter 8. The DbLsn Handle">DbLsn</a> file offsets are
unsigned four-byte values, the set value may not be larger than the
maximum unsigned four-byte value.
</p>
<p>
When the logging subsystem is configured for on-disk logging, the
default size of a log file is 10MB.
</p>
<p>
When the logging subsystem is configured for in-memory logging, the
default size of a log file is 256KB. In addition, the configured log
buffer size must be larger than the log file size. (The logging
subsystem divides memory configured for in-memory log records into
"files", as database environments configured for in-memory log records
may exchange log records with other members of a replication group,
and those members may be configured to store log records on-disk.)
When choosing log buffer and file sizes for in-memory logs,
applications should ensure the in-memory log buffer size is large
enough that no transaction will ever span the entire buffer, and avoid
a state where the in-memory buffer is full and no space can be freed
because a transaction that started in the first log "file" is still
active.
</p>
<p>
See <a href="../../programmer_reference/log_limits.html" class="olink">Log File Limits</a> for
more information.
</p>
<p>
The database environment's log file size may also be configured using
the environment's <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file. The
syntax of the entry in that file is a single line with the string
"set_lg_max", one or more whitespace characters, and the size in
bytes. Because the <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file is
read when the database environment is opened, it will silently
overrule configuration done before that time.
</p>
<p>
The <code class="methodname">DbEnv::set_lg_max()</code> method configures a database environment,
not only operations performed using the specified
<a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a> handle.
</p>
<p>
The <code class="methodname">DbEnv::set_lg_max()</code> method may be called at any time during the
life of the application.
</p>
<p>
If no size is specified by the application, the size last specified
for the database region will be used, or if no database region
previously existed, the default will be used.
</p>
<p>
The <code class="methodname">DbEnv::set_lg_max()</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="id1688530"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id1688360"></a>lg_max</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>lg_max</strong></span> parameter is the size of a
single log file, in bytes.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1688682"></a>Errors</h3>
</div>
</div>
</div>
<p>
The <code class="methodname">DbEnv::set_lg_max()</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="id1688386"></a>EINVAL</h4>
</div>
</div>
</div>
<p>
If the size of the log file is less than four
times the size of the in-memory log buffer;
the specified log file size was too large; 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="id1688490"></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="id1688519"></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>
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