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118 lines
5.3 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>db close</title>
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<link rel="stylesheet" href="apiReference.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 TCL API Reference" />
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<link rel="up" href="tclapi.html" title="Chapter 1. Berkeley DB Tcl APIs" />
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<link rel="prev" href="tclapi.html" title="Chapter 1. Berkeley DB Tcl APIs" />
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<link rel="next" href="db_count.html" title="db count" />
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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"><span xmlns="http://www.w3.org/1999/xhtml" class="emphasis"><em>db</em></span> close</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="tclapi.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 1.
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Berkeley DB Tcl APIs
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</th>
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<td width="20%" align="right"> <a accesskey="n" href="db_count.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="db_close"></a><span class="emphasis"><em>db</em></span> close</h2>
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</div>
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</div>
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</div>
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<pre class="programlisting">db close
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[-nosync] </pre>
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<p>
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The <span class="emphasis"><em>db</em></span> <span class="bold"><strong>close</strong></span>
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command flushes any cached database information to disk, closes any
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open cursors, frees any allocated resources, and closes any underlying
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files. Because key/data pairs are cached in memory, failing to sync
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the file with the <span class="emphasis"><em>db</em></span> <span class="bold"><strong>close</strong></span> or <span class="emphasis"><em>db</em></span> <span class="bold"><strong>sync</strong></span> command may result in inconsistent or lost
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information.
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</p>
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<p>
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The options are as follows:
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</p>
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<div class="itemizedlist">
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<ul type="disc">
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<li>
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<p>
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<span class="bold"><strong>-nosync</strong></span>
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</p>
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<p>
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Do not flush cached information to disk.
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</p>
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<p>
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The <code class="literal">-nosync</code> flag is a dangerous option. It should only be set if the
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application is doing logging (with transactions) so that the database
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is recoverable after a system or application crash, or if the database
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is always generated from scratch after any system or application
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crash.
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</p>
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<p>
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It is important to understand that flushing cached information to disk
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only minimizes the window of opportunity for corrupted data. Although
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unlikely, it is possible for database corruption to happen if a system
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or application crash occurs while writing data to the database. To
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ensure that database corruption never occurs, applications must either
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use transactions and logging with automatic recovery, use logging and
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application-specific recovery, or edit a copy of the database; and
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after all applications using the database have successfully called
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<span class="emphasis"><em>db</em></span> <span class="bold"><strong>close</strong></span>,
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atomically replace the original database with the updated copy.
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</p>
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</li>
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</ul>
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</div>
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<p>
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After <span class="emphasis"><em>db</em></span> <span class="bold"><strong>close</strong></span>
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has been called, regardless of its return, the DB handle may not be
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accessed again.
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</p>
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<p>
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The <span class="emphasis"><em>db</em></span> <span class="bold"><strong>close</strong></span>
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command returns 0 on success, and in the case of error, a Tcl error is
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thrown.
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</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="tclapi.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="tclapi.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="db_count.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 1.
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Berkeley DB Tcl APIs
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</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"> <span class="emphasis"><em>db</em></span> count</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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