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105 lines
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HTML
105 lines
5 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>database open/close</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_3_0_toc.html" title="Chapter 14. Upgrading Berkeley DB 2.X applications to Berkeley DB 3.0" />
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<link rel="prev" href="upgrade_3_0_dbenv.html" title="DB_ENV structure" />
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<link rel="next" href="upgrade_3_0_xa.html" title="db_xa_open" />
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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">database open/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="upgrade_3_0_dbenv.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 14. Upgrading Berkeley DB 2.X applications to Berkeley DB 3.0</th>
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<td width="20%" align="right"> <a accesskey="n" href="upgrade_3_0_xa.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_3_0_open"></a>database open/close</h2>
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</div>
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</div>
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</div>
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<p>Database opens were changed in the Berkeley DB 3.0 release in a similar way to
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environment opens.</p>
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<p>To upgrade your application, first find each place your application opens
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a database, that is, calls the db_open function. Each of these calls
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should be replaced with calls to <a href="../api_reference/C/dbcreate.html" class="olink">db_create()</a> and <a href="../api_reference/C/dbopen.html" class="olink">DB->open()</a>.</p>
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<p>Here's an example creating a Berkeley DB database using the 2.X interface:</p>
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<pre class="programlisting">DB *dbp;
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DB_ENV *dbenv;
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int ret;
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if ((ret = db_open(DATABASE,
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DB_BTREE, DB_CREATE, 0664, dbenv, NULL, &dbp)) != 0)
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return (ret);</pre>
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<p>In the Berkeley DB 3.0 release, this code would be written as:</p>
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<pre class="programlisting">DB *dbp;
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DB_ENV *dbenv;
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int ret;
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if ((ret = db_create(&dbp, dbenv, 0)) != 0)
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return (ret);
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if ((ret = dbp->open(dbp,
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DATABASE, NULL, DB_BTREE, DB_CREATE, 0664)) != 0) {
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(void)dbp->close(dbp, 0);
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return (ret);
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}</pre>
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<p>As you can see, the arguments to db_open and to <a href="../api_reference/C/dbopen.html" class="olink">DB->open()</a> are
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largely the same. There is some re-organization, and note that the
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enclosing <a href="../api_reference/C/env.html" class="olink">DB_ENV</a> structure is specified when the <a href="../api_reference/C/db.html" class="olink">DB</a> object
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is created using the <a href="../api_reference/C/dbcreate.html" class="olink">db_create()</a> function. There is one
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additional argument to <a href="../api_reference/C/dbopen.html" class="olink">DB->open()</a>, argument #3. For backward
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compatibility with the 2.X Berkeley DB releases, simply set that argument to
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NULL.</p>
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<p>There are two additional issues with the db_open call.</p>
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<p>First, it was possible in the 2.X releases for an application to provide
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an environment that did not contain a shared memory buffer pool as the
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database environment, and Berkeley DB would create a private one automatically.
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This functionality is no longer available, applications must specify the
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<a href="../api_reference/C/envopen.html#envopen_DB_INIT_MPOOL" class="olink">DB_INIT_MPOOL</a> flag if databases are going to be opened in the
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environment.</p>
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<p>The final issue with upgrading the db_open call is that the DB_INFO
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structure is no longer used, having been replaced by individual methods
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on the <a href="../api_reference/C/db.html" class="olink">DB</a> handle. That change is discussed in detail later in
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this chapter.</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_3_0_dbenv.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="upgrade_3_0_toc.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="upgrade_3_0_xa.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_ENV structure </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"> db_xa_open</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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