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<h2 class="title" style="clear: both"><a id="dbupgrade"></a>Db::upgrade()</h2>
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<pre class="programlisting">#include <db_cxx.h>
int
Db::upgrade(const char *file, u_int32_t flags);</pre>
<p>
The <code class="methodname">Db::upgrade()</code> method upgrades all of the databases included in
the file <span class="bold"><strong>file</strong></span>, if necessary. If no
upgrade is necessary, <code class="methodname">Db::upgrade()</code> always returns success.
</p>
<p>
<span class="bold"><strong>Database upgrades are done in place and are
destructive. For example, if pages need to be allocated and no disk
space is available, the database may be left corrupted. Backups
should be made before databases are upgraded. See <a href="../../programmer_reference/am_upgrade.html" class="olink">Upgrading databases</a> for more
information.</strong></span>
</p>
<p>
Unlike all other database operations, <code class="methodname">Db::upgrade()</code> may only be done
on a system with the same byte-order as the database.
</p>
<p>
The <code class="methodname">Db::upgrade()</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="id1653658"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id1653756"></a>file</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>file</strong></span> parameter is the physical
file containing the databases to be upgraded.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id1653563"></a>flags</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>flags</strong></span> parameter must be set to 0
or the following value:
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p><a id="upgrade_DB_DUPSORT"></a>
<code class="literal">DB_DUPSORT</code>
</p>
<p>
<span class="bold"><strong>This flag is only meaningful when upgrading
databases from releases before the Berkeley DB 3.1 release.</strong></span>
</p>
<p>
As part of the upgrade from the Berkeley DB 3.0 release to the 3.1
release, the on-disk format of duplicate data items changed. To
correctly upgrade the format requires applications to specify whether
duplicate data items in the database are sorted or not. Specifying
the DB_DUPSORT flag informs <code class="methodname">Db::upgrade()</code> that the duplicates are
sorted; otherwise they are assumed to be unsorted. Incorrectly
specifying the value of this flag may lead to database corruption.
</p>
<p>
Further, because the <code class="methodname">Db::upgrade()</code> method upgrades a physical file
(including all the databases it contains), it is not possible to use
<code class="methodname">Db::upgrade()</code> to upgrade files in which some of the databases it
includes have sorted duplicate data items, and some of the databases
it includes have unsorted duplicate data items. If the file does not
have more than a single database, if the databases do not support
duplicate data items, or if all of the databases that support
duplicate data items support the same style of duplicates (either
sorted or unsorted), <code class="methodname">Db::upgrade()</code> will work correctly as long as the
DB_DUPSORT flag is correctly specified. Otherwise, the file cannot be
upgraded using <code class="methodname">Db::upgrade;()</code> it must be upgraded manually by dumping
and reloading the databases.
</p>
</li>
</ul>
</div>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1654069"></a>Environment Variables</h3>
</div>
</div>
</div>
<p>
If the database was opened within a database environment, the
environment variable <code class="literal">DB_HOME</code> may be used as the path of the
database environment home.
</p>
<p>
<code class="methodname">Db::upgrade()</code> is affected by any database directory specified using the
<a class="xref" href="envset_data_dir.html" title="DbEnv::set_data_dir()">DbEnv::set_data_dir()</a>
method, or by setting the "set_data_dir" string in the environment's
<a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a>
file.
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1654061"></a>Errors</h3>
</div>
</div>
</div>
<p>
The <code class="methodname">Db::upgrade()</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="id1653925"></a>DB_OLD_VERSION</h4>
</div>
</div>
</div>
<p>
The database cannot be upgraded by this version of the Berkeley DB
software.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1653762"></a>Class</h3>
</div>
</div>
</div>
<p>
<a class="link" href="db.html" title="Chapter 2. The Db Handle">Db</a>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1653755"></a>See Also</h3>
</div>
</div>
</div>
<p>
<a class="xref" href="db.html#dblist" title="Database and Related Methods">Database and Related Methods</a>
</p>
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