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https://github.com/yasuhirokimura/db18
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Yasuhiro KIMURA
104 lines
4.3 KiB
HTML
104 lines
4.3 KiB
HTML
<?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>Why transactions?</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 Programmer's Reference Guide" />
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<link rel="up" href="transapp.html" title="Chapter 11. Berkeley DB Transactional Data Store Applications" />
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<link rel="prev" href="transapp.html" title="Chapter 11. Berkeley DB Transactional Data Store Applications" />
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<link rel="next" href="transapp_term.html" title="Terminology" />
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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 18.1.40</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">Why transactions?</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="transapp.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 11. Berkeley DB Transactional Data Store Applications </th>
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<td width="20%" align="right"> <a accesskey="n" href="transapp_term.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="transapp_why"></a>Why transactions?</h2>
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</div>
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</div>
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</div>
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<p>
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Perhaps the first question to answer is "Why transactions?"
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There are a number of reasons to include transactional support
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in your applications. The most common ones are the
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following:
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</p>
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<div class="variablelist">
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<dl>
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<dt>
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<span class="term">Recoverability</span>
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</dt>
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<dd>
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Applications often need to ensure that no matter
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how the system or application fails, previously saved
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data is available the next time the application runs.
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This is often called Durability.
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</dd>
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<dt>
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<span class="term">Atomicity</span>
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</dt>
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<dd>
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Applications may need to make multiple changes
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to one or more databases, but ensure that either all
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of the changes happen, or none of them happens.
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Transactions guarantee that a group of changes are
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atomic; that is, if the application or system fails,
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either all of the changes to the databases will appear
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when the application next runs, or none of
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them.
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</dd>
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<dt>
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<span class="term">Isolation</span>
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</dt>
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<dd>
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Applications may need to make changes in
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isolation, that is, ensure that only a single thread
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of control is modifying a key/data pair at a time.
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Transactions ensure each thread of control sees all
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records as if all other transactions either completed
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before or after its transaction.
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</dd>
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</dl>
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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="transapp.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="transapp.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="transapp_term.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">Chapter 11. Berkeley DB Transactional Data Store Applications </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"> Terminology</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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