105 lines
4.8 KiB
HTML
105 lines
4.8 KiB
HTML
<!--$Id: db_upgrade.html 63573 2008-05-23 21:43:21Z trent.nelson $-->
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<!--Copyright (c) 1997,2008 Oracle. All rights reserved.-->
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<!--See the file LICENSE for redistribution information.-->
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<html>
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<head>
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<title>Berkeley DB: Db::upgrade</title>
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<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
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<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++">
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</head>
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<body bgcolor=white>
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<table width="100%"><tr valign=top>
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<td>
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<b>Db::upgrade</b>
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</td>
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<td align=right>
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<a href="../api_cxx/api_core.html"><img src="../images/api.gif" alt="API"></a>
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<a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a></td>
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</tr></table>
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<hr size=1 noshade>
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<tt>
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<b><pre>
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#include <db_cxx.h>
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<p>
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int
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Db::upgrade(const char *file, u_int32_t flags);
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</pre></b>
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<hr size=1 noshade>
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<b>Description: Db::upgrade</b>
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<p>The Db::upgrade method upgrades all of the databases included in the
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file <b>file</b>, if necessary. If no upgrade is necessary,
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Db::upgrade always returns success.</p>
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<p><b>Database upgrades are done in place and are destructive. For example,
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if pages need to be allocated and no disk space is available, the
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database may be left corrupted. Backups should be made before databases
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are upgraded. See <a href="../ref/am/upgrade.html">Upgrading databases</a>
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for more information.</b></p>
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<p>Unlike all other database operations, Db::upgrade may only be done
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on a system with the same byte-order as the database.</p>
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<p>The Db::upgrade method
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either returns a non-zero error value
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or throws an exception that encapsulates a non-zero error value on
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failure, and returns 0 on success.
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</p>
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<b>Parameters</b> <br>
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<b>file</b><ul compact><li>The <b>file</b> parameter is the physical file containing the databases
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to be upgraded.</ul>
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<b>flags</b><ul compact><li>The <b>flags</b> parameter must be set to 0 or
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the following value:
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<br>
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<b><a name="DB_DUPSORT">DB_DUPSORT</a></b><ul compact><li><b>This flag is only meaningful when upgrading databases from
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releases before the Berkeley DB 3.1 release.</b>
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<p>As part of the upgrade from the Berkeley DB 3.0 release to the 3.1 release,
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the on-disk format of duplicate data items changed. To correctly
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upgrade the format requires applications to specify whether duplicate
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data items in the database are sorted or not. Specifying the
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DB_DUPSORT flag informs Db::upgrade that the duplicates
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are sorted; otherwise they are assumed to be unsorted. Incorrectly
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specifying the value of this flag may lead to database corruption.</p>
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<p>Further, because the Db::upgrade method upgrades a physical file
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(including all the databases it contains), it is not possible to use
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Db::upgrade to upgrade files in which some of the databases it
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includes have sorted duplicate data items, and some of the databases it
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includes have unsorted duplicate data items. If the file does not have
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more than a single database, if the databases do not support duplicate
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data items, or if all of the databases that support duplicate data items
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support the same style of duplicates (either sorted or unsorted),
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Db::upgrade will work correctly as long as the
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DB_DUPSORT flag is correctly specified. Otherwise, the file
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cannot be upgraded using Db::upgrade; it must be upgraded
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manually by dumping and reloading the databases.</p></ul>
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<br></ul>
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<br>
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<br><b>Environment Variables</b>
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<p>If the database was opened within a database environment, the
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environment variable <b>DB_HOME</b> may be used as the path of the
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database environment home.</p>
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<p>Db::upgrade is affected by any database directory specified using
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the <a href="../api_cxx/env_set_data_dir.html">DbEnv::set_data_dir</a> method, or by setting the "set_data_dir" string
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in the environment's <a href="../ref/env/db_config.html#DB_CONFIG">DB_CONFIG</a> file.</p>
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<br><b>Errors</b>
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<p>The Db::upgrade method
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may fail and throw
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<a href="../api_cxx/except_class.html">DbException</a>,
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encapsulating one of the following non-zero errors, or return one of
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the following non-zero errors:</p>
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<br>
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<b><a name="DB_OLD_VERSION">DB_OLD_VERSION</a></b><ul compact><li>The database cannot be upgraded by this version of the Berkeley DB software.</ul>
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<br>
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<br>
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<b>EINVAL</b><ul compact><li>If the database is not in the same byte-order as the system; or if an
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invalid flag value or parameter was specified.</ul>
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<br>
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<hr size=1 noshade>
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<br><b>Class</b>
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<a href="../api_cxx/db_class.html">Db</a>
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<br><b>See Also</b>
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<a href="../api_cxx/db_list.html">Databases and Related Methods</a>
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</tt>
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<table width="100%"><tr><td><br></td><td align=right>
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<a href="../api_cxx/api_core.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a>
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</td></tr></table>
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<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font>
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</body>
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</html>
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