110 lines
4.2 KiB
HTML
110 lines
4.2 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>Closing Databases</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 V1.62.4" />
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<link rel="home" href="index.html" title="Getting Started with Berkeley DB" />
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<link rel="up" href="DB.html" title="Chapter 2. Databases" />
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<link rel="previous" href="DB.html" title="Chapter 2. Databases" />
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<link rel="next" href="DBOpenFlags.html" title="Database Open Flags" />
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</head>
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<body>
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<div class="navheader">
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">Closing Databases</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="DB.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 2. Databases</th>
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<td width="20%" align="right"> <a accesskey="n" href="DBOpenFlags.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="coredbclose"></a>Closing Databases</h2>
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</div>
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</div>
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<div></div>
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</div>
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<p>
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Once you are done using the database, you must close it. You use the
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<tt class="methodname">Db::close()</tt>
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method to do this.
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</p>
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<p>
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Closing a database causes it to become unusable until it is opened
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again. Note that you should make sure that any open cursors are closed
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before closing your database. Active cursors during a database
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close can cause unexpected results, especially if any of those cursors are
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writing to the database. You should always make sure that all your
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database accesses have completed before closing your database.
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</p>
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<p>
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Cursors are described in <a href="Cursors.html">Using Cursors</a> later in this manual.
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</p>
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<p>
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Be aware that when you close the last open handle
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for a database, then by default its cache is flushed to disk.
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This means that any information that has
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been modified in the cache is guaranteed to be written to disk when the
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last handle is closed. You can manually perform this operation using
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the
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<tt class="methodname">Db::sync()</tt>
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method, but for normal shutdown operations it is not necessary.
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For more information about syncing your cache, see
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<a href="usingDbt.html#datapersist">Data Persistence</a>.
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</p>
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<p>The following code fragment illustrates a database close:</p>
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<a id="cxx_db2"></a>
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<pre class="programlisting">#include <db_cxx.h>
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...
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Db db(NULL, 0);
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// Database open and access operations happen here.
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try {
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// Close the database
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db.close(0);
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// DbException is not subclassed from std::exception, so
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// need to catch both of these.
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} catch(DbException &e) {
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// Error handling code goes here
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} catch(std::exception &e) {
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// Error handling code goes here
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} </pre>
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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="DB.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="DB.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="DBOpenFlags.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 2. Databases </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"> Database Open Flags</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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