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103 lines
4.9 KiB
HTML
103 lines
4.9 KiB
HTML
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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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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>DB_JOINENV</title>
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<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
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<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
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<link rel="start" href="index.html" title="Berkeley DB Upgrade Guide" />
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<link rel="up" href="upgrade_4_4_toc.html" title="Chapter 6. Upgrading Berkeley DB 4.3 applications to Berkeley DB 4.4" />
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<link rel="prev" href="upgrade_4_4_isolation.html" title="DB_DEGREE_2, DB_DIRTY_READ" />
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<link rel="next" href="upgrade_4_4_mutex.html" title="mutexes" />
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</head>
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<body>
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<div xmlns="" class="navheader">
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<div class="libver">
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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">DB_JOINENV</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="upgrade_4_4_isolation.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 6. Upgrading Berkeley DB 4.3 applications to Berkeley DB 4.4</th>
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<td width="20%" align="right"> <a accesskey="n" href="upgrade_4_4_mutex.html">Next</a></td>
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</tr>
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</table>
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<hr />
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</div>
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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="upgrade_4_4_joinenv"></a>DB_JOINENV</h2>
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</div>
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</div>
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</div>
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<p>The semantics of joining existing Berkeley DB database environments has changed
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in the 4.4 release. Previously:</p>
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<div class="orderedlist">
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<ol type="1">
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<li>Applications joining existing environments, but not configuring some of
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the subsystems configured in the environment when it was created, would
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not be configured for those subsystems.</li>
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<li>Applications joining existing environments, but configuring additional
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subsystems in addition to the subsystems configured in the environment
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when it was created, would cause additional subsystems to be configured
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in the database environment.</li>
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</ol>
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</div>
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<p>In the 4.4 release, the semantics have been simplified to make it easier
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to write robust applications. In the 4.4 release:</p>
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<div class="orderedlist">
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<ol type="1">
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<li>Applications joining existing environments, but not configuring some of
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the subsystems configured in the environment when it was created, will
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now automatically be configured for all of the subsystems configured in
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the environment.</li>
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<li>Applications joining existing environments, but configuring additional
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subsystems in addition to the subsystems configured in the environment
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when it was created, will fail, as no additional subsystems can be
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configured for a database environment after it is created.</li>
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</ol>
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</div>
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<p>In other words, the choice of subsystems initialized for a Berkeley DB
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database environment is specified by the thread of control initially
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creating the environment. Any subsequent thread of control joining the
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environment will automatically be configured to use the same subsystems
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as were created in the environment (unless the thread of control
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requests a subsystem not available in the environment, which will fail).
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Applications joining an environment, able to adapt to whatever
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subsystems have been configured in the environment, should open the
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environment without specifying any subsystem flags. Applications
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joining an environment, requiring specific subsystems from their
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environments, should open the environment specifying those specific
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subsystem flags.</p>
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<p>The DB_JOINENV flag has been changed to have no effect in the Berkeley DB 4.4
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release. Applications should require no changes, although uses of the
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DB_JOINENV flag may be removed.</p>
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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="upgrade_4_4_isolation.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="upgrade_4_4_toc.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="upgrade_4_4_mutex.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">DB_DEGREE_2, DB_DIRTY_READ </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"> mutexes</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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