1<!--$Id: open.so,v 11.11 2003/10/18 19:16:14 bostic Exp $--> 2<!--Copyright (c) 1997,2008 Oracle. All rights reserved.--> 3<!--See the file LICENSE for redistribution information.--> 4<html> 5<head> 6<title>Berkeley DB Reference Guide: Release 3.0: database open/close</title> 7<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> 8<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> 9</head> 10<body bgcolor=white> 11<table width="100%"><tr valign=top> 12<td><b><dl><dt>Berkeley DB Reference Guide:<dd>Upgrading Berkeley DB Applications</dl></b></td> 13<td align=right><a href="/upgrade.3.0/dbenv.html"><img src="/images/prev.gif" alt="Prev"></a><a href="/toc.html"><img src="/images/ref.gif" alt="Ref"></a><a href="/upgrade.3.0/xa.html"><img src="/images/next.gif" alt="Next"></a> 14</td></tr></table> 15<p align=center><b>Release 3.0: database open/close</b></p> 16<p>Database opens were changed in the Berkeley DB 3.0 release in a similar way to 17environment opens.</p> 18<p>To upgrade your application, first find each place your application opens 19a database, that is, calls the db_open function. Each of these calls 20should be replaced with calls to <a href="/api_c/db_class.html">db_create</a> and <a href="/api_c/db_open.html">DB->open</a>.</p> 21<p>Here's an example creating a Berkeley DB database using the 2.X interface:</p> 22<blockquote><pre>DB *dbp; 23DB_ENV *dbenv; 24int ret; 25<p> 26if ((ret = db_open(DATABASE, 27 DB_BTREE, DB_CREATE, 0664, dbenv, NULL, &dbp)) != 0) 28 return (ret);</pre></blockquote> 29<p>In the Berkeley DB 3.0 release, this code would be written as:</p> 30<blockquote><pre>DB *dbp; 31DB_ENV *dbenv; 32int ret; 33<p> 34if ((ret = db_create(&dbp, dbenv, 0)) != 0) 35 return (ret); 36<p> 37if ((ret = dbp->open(dbp, 38 DATABASE, NULL, DB_BTREE, DB_CREATE, 0664)) != 0) { 39 (void)dbp->close(dbp, 0); 40 return (ret); 41}</pre></blockquote> 42<p>As you can see, the arguments to db_open and to <a href="/api_c/db_open.html">DB->open</a> are 43largely the same. There is some re-organization, and note that the 44enclosing <a href="/api_c/env_class.html">DB_ENV</a> structure is specified when the <a href="/api_c/db_class.html">DB</a> object 45is created using the <a href="/api_c/db_class.html">db_create</a> function. There is one 46additional argument to <a href="/api_c/db_open.html">DB->open</a>, argument #3. For backward 47compatibility with the 2.X Berkeley DB releases, simply set that argument to 48NULL.</p> 49<p>There are two additional issues with the db_open call.</p> 50<p>First, it was possible in the 2.X releases for an application to provide 51an environment that did not contain a shared memory buffer pool as the 52database environment, and Berkeley DB would create a private one automatically. 53This functionality is no longer available, applications must specify the 54<a href="/api_c/env_open.html#DB_INIT_MPOOL">DB_INIT_MPOOL</a> flag if databases are going to be opened in the 55environment.</p> 56<p>The final issue with upgrading the db_open call is that the DB_INFO 57structure is no longer used, having been replaced by individual methods 58on the <a href="/api_c/db_class.html">DB</a> handle. That change is discussed in detail later in 59this chapter.</p> 60<table width="100%"><tr><td><br></td><td align=right><a href="/upgrade.3.0/dbenv.html"><img src="/images/prev.gif" alt="Prev"></a><a href="/toc.html"><img src="/images/ref.gif" alt="Ref"></a><a href="/upgrade.3.0/xa.html"><img src="/images/next.gif" alt="Next"></a> 61</td></tr></table> 62<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> 63</body> 64</html> 65
