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210 lines
8.8 KiB
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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>DbEnv::set_lg_max()</title>
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<link rel="up" href="lsn.html" title="Chapter 8. The DbLsn Handle" />
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<link rel="prev" href="envset_lg_filemode.html" title="DbEnv::set_lg_filemode()" />
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<p>Library Version 11.2.5.2</p>
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</div>
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">DbEnv::set_lg_max()</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="envset_lg_filemode.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 8.
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The DbLsn Handle
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</th>
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<td width="20%" align="right"> <a accesskey="n" href="envset_lg_regionmax.html">Next</a></td>
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<div class="sect1" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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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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</div>
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</div>
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</div>
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<pre class="programlisting">#include <db_cxx.h>
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int
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DbEnv::set_lg_max(u_int32_t lg_max); </pre>
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<p>
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Sets the maximum size of a single file in the log, in bytes. Because
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<a class="link" href="lsn.html" title="Chapter 8. The DbLsn Handle">DbLsn</a> file offsets are
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unsigned four-byte values, the set value may not be larger than the
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maximum unsigned four-byte value.
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</p>
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<p>
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When the logging subsystem is configured for on-disk logging, the
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default size of a log file is 10MB.
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</p>
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<p>
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When the logging subsystem is configured for in-memory logging, the
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default size of a log file is 256KB. In addition, the configured log
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buffer size must be larger than the log file size. (The logging
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subsystem divides memory configured for in-memory log records into
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"files", as database environments configured for in-memory log records
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may exchange log records with other members of a replication group,
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and those members may be configured to store log records on-disk.)
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When choosing log buffer and file sizes for in-memory logs,
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applications should ensure the in-memory log buffer size is large
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enough that no transaction will ever span the entire buffer, and avoid
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a state where the in-memory buffer is full and no space can be freed
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because a transaction that started in the first log "file" is still
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active.
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</p>
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<p>
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See <a href="../../programmer_reference/log_limits.html" class="olink">Log File Limits</a> for
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more information.
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</p>
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<p>
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The database environment's log file size may also be configured
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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
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in that file is a single line with the string "set_lg_max", one or
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more whitespace characters, and the size in bytes. Because the
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<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,
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it will silently overrule configuration done before that time.
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</p>
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<p>
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The <code class="methodname">DbEnv::set_lg_max()</code> method configures a database environment,
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not only operations performed using the specified
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<a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a> handle.
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</p>
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<p>
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The <code class="methodname">DbEnv::set_lg_max()</code> method may be called at any time during the
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life of the application.
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</p>
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<p>
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If no size is specified by the application, the size last specified
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for the database region will be used, or if no database region
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previously existed, the default will be used.
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</p>
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<p>
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The <code class="methodname">DbEnv::set_lg_max()</code> <span>
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<span>
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method either returns a non-zero error value or throws an
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exception that encapsulates a non-zero error value on
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failure, and returns 0 on success.
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</span>
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</span>
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</p>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3641499"></a>Parameters</h3>
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</div>
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</div>
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</div>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h4 class="title"><a id="id3641491"></a>lg_max</h4>
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</div>
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</div>
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</div>
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<p>
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The <span class="bold"><strong>lg_max</strong></span> parameter is the size of a
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single log file, in bytes.
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</p>
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</div>
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</div>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3641545"></a>Errors</h3>
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</div>
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</div>
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</div>
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<p>
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The <code class="methodname">DbEnv::set_lg_max()</code> <span>
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<span>
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method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a>
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exception, encapsulating one of the following non-zero errors, or return one
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of the following non-zero errors:
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</span>
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</span>
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</p>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h4 class="title"><a id="id3641714"></a>EINVAL</h4>
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</div>
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</div>
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</div>
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<p>
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If the size of the log file is less than four
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times the size of the in-memory log buffer;
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the specified log file size was too large; or
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if an invalid flag value or parameter was
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specified.
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</p>
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</div>
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</div>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3641696"></a>Class</h3>
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</div>
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</div>
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</div>
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<p>
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<a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a>,
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<a class="link" href="logc.html" title="The DbLogc Handle">DbLogc</a>,
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<a class="link" href="lsn.html" title="Chapter 8. The DbLsn Handle">DbLsn</a>
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</p>
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</div>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3641224"></a>See Also</h3>
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</div>
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</div>
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</div>
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<p>
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<a class="xref" href="lsn.html#loglist" title="Logging Subsystem and Related Methods">Logging Subsystem and Related Methods</a>
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</p>
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</div>
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</div>
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<div class="navfooter">
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<hr />
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<table width="100%" summary="Navigation footer">
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<tr>
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<td width="40%" align="left"><a accesskey="p" href="envset_lg_filemode.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="lsn.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="envset_lg_regionmax.html">Next</a></td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">DbEnv::set_lg_filemode() </td>
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<td width="20%" align="center">
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> DbEnv::set_lg_regionmax()</td>
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</tr>
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</table>
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</div>
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</body>
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</html>
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