119 lines
4.2 KiB
HTML
119 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>Database Open Flags</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="coredbclose.html" title="Closing Databases" />
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<link rel="next" href="CoreDBAdmin.html" title="Administrative Methods" />
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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">Database Open Flags</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="coredbclose.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="CoreDBAdmin.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="DBOpenFlags"></a>Database Open Flags</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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The following are the flags that you may want to use at database open time.
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Note that this list is not exhaustive — it includes only those flags likely
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to be of interest for introductory, single-threaded
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database applications. For a complete list of the flags available to you, see the
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<i class="citetitle">Berkeley DB C++ API guide.</i>
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</p>
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<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
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<h3 class="title">Note</h3>
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<p>
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To specify more than one flag on the call to
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<span><tt class="methodname">Db::open()</tt>,</span>
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you must bitwise inclusively OR them together:
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</p>
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<a id="c_db3"></a>
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<pre class="programlisting">u_int32_t open_flags = DB_CREATE | DB_EXCL;</pre>
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</div>
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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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<tt class="literal">DB_CREATE</tt>
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</p>
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<p>
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If the database does not currently exist, create it. By default, the database open
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fails if the database does not already exist.
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</p>
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</li>
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<li>
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<p>
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<tt class="literal">DB_EXCL</tt>
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</p>
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<p>
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Exclusive database creation. Causes the database open to fail if the database
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already exists. This flag is only meaningful when used with
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<tt class="literal">DB_CREATE</tt>.
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</p>
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</li>
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<li>
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<p>
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<tt class="literal">DB_RDONLY</tt>
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</p>
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<p>
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Open the database for read operations only. Causes any subsequent database write
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operations to fail.
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</p>
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</li>
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<li>
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<p>
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<tt class="literal">DB_TRUNCATE</tt>
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</p>
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<p>
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Physically truncate (empty) the on-disk file that contains the database.
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Causes DB to delete all databases physically contained in that file.
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</p>
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</li>
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</ul>
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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="coredbclose.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="CoreDBAdmin.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">Closing 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"> Administrative Methods</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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