<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>Release 3.0: database open/close</title> <link rel="stylesheet" href="gettingStarted.css" type="text/css" /> <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> <link rel="start" href="index.html" title="Berkeley DB Programmer's Reference Guide" /> <link rel="up" href="upgrade_3_0_toc.html" title="Chapter 33. Upgrading Berkeley DB 2.X applications to Berkeley DB 3.0" /> <link rel="prev" href="upgrade_3_0_dbenv.html" title="Release 3.0: the DB_ENV structure" /> <link rel="next" href="upgrade_3_0_xa.html" title="Release 3.0: db_xa_open" /> </head> <body> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">Release 3.0: database open/close</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="upgrade_3_0_dbenv.html">Prev</a> </td> <th width="60%" align="center">Chapter 33. Upgrading Berkeley DB 2.X applications to Berkeley DB 3.0</th> <td width="20%" align="right"> <a accesskey="n" href="upgrade_3_0_xa.html">Next</a></td> </tr> </table> <hr /> </div> <div class="sect1" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h2 class="title" style="clear: both"><a id="upgrade_3_0_open"></a>Release 3.0: database open/close</h2> </div> </div> </div> <p>Database opens were changed in the Berkeley DB 3.0 release in a similar way to environment opens.</p> <p>To upgrade your application, first find each place your application opens a database, that is, calls the db_open function. Each of these calls 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> <p>Here's an example creating a Berkeley DB database using the 2.X interface:</p> <pre class="programlisting">DB *dbp; DB_ENV *dbenv; int ret; if ((ret = db_open(DATABASE, DB_BTREE, DB_CREATE, 0664, dbenv, NULL, &dbp)) != 0) return (ret);</pre> <p>In the Berkeley DB 3.0 release, this code would be written as:</p> <pre class="programlisting">DB *dbp; DB_ENV *dbenv; int ret; if ((ret = db_create(&dbp, dbenv, 0)) != 0) return (ret); if ((ret = dbp->open(dbp, DATABASE, NULL, DB_BTREE, DB_CREATE, 0664)) != 0) { (void)dbp->close(dbp, 0); return (ret); }</pre> <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 largely the same. There is some re-organization, and note that the 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 is created using the <a href="../api_reference/C/dbcreate.html" class="olink">db_create()</a> function. There is one additional argument to <a href="../api_reference/C/dbopen.html" class="olink">DB->open()</a>, argument #3. For backward compatibility with the 2.X Berkeley DB releases, simply set that argument to NULL.</p> <p>There are two additional issues with the db_open call.</p> <p>First, it was possible in the 2.X releases for an application to provide an environment that did not contain a shared memory buffer pool as the database environment, and Berkeley DB would create a private one automatically. This functionality is no longer available, applications must specify the <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 environment.</p> <p>The final issue with upgrading the db_open call is that the DB_INFO structure is no longer used, having been replaced by individual methods on the <a href="../api_reference/C/db.html" class="olink">DB</a> handle. That change is discussed in detail later in this chapter.</p> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="upgrade_3_0_dbenv.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="upgrade_3_0_toc.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="upgrade_3_0_xa.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">Release 3.0: the DB_ENV structure </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> Release 3.0: db_xa_open</td> </tr> </table> </div> </body> </html>