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<title>Berkeley DB Reference Guide: Release 3.0: the DbEnv class for C++ and Java</title>
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<td><dl><dt>Berkeley DB Reference Guide:<dd>Upgrading Berkeley DB Applications</dl></td>
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Release 3.0: the DbEnv class for C++ and Java
The DbEnv::appinit() method and two constructors for the DbEnv class are
gone. There is now a single way to create and initialize the environment.
The way to create an environment is to use the new DbEnv constructor with
one argument. After this call, the DbEnv can be configured with various
set_XXX methods. Finally, a call to DbEnv::open is made to initialize
the environment.
Here's a C++ example creating a Berkeley DB environment using the 2.X interface
<blockquote><pre>int dberr;
DbEnv *dbenv = new DbEnv();

dbenv-&gt;set_error_stream(&cerr);
dbenv-&gt;set_errpfx("myprog");

if ((dberr = dbenv-&gt;appinit("/database/home",
	NULL, DB_CREATE | DB_INIT_LOCK | DB_INIT_MPOOL)) != 0) {
 cerr &lt;&lt; "failure: " &lt;&lt; strerror(dberr);
 exit (1);
}</pre></blockquote>
In the Berkeley DB 3.0 release, this code would be written as:
<blockquote><pre>int dberr;
DbEnv *dbenv = new DbEnv(0);

dbenv-&gt;set_error_stream(&cerr);
dbenv-&gt;set_errpfx("myprog");

if ((dberr = dbenv-&gt;open("/database/home",
	NULL, DB_CREATE | DB_INIT_LOCK | DB_INIT_MPOOL, 0)) != 0) {
 cerr &lt;&lt; "failure: " &lt;&lt; dbenv-&gt;strerror(dberr);
 exit (1);
}</pre></blockquote>
Here's a Java example creating a Berkeley DB environment using the 2.X interface:
<blockquote><pre>int dberr;
DbEnv dbenv = new DbEnv();

dbenv.set_error_stream(System.err);
dbenv.set_errpfx("myprog");

dbenv.appinit("/database/home",
 null, Db.DB_CREATE | Db.DB_INIT_LOCK | Db.DB_INIT_MPOOL);</pre></blockquote>
In the Berkeley DB 3.0 release, this code would be written as:
<blockquote><pre>int dberr;
DbEnv dbenv = new DbEnv(0);

dbenv.set_error_stream(System.err);
dbenv.set_errpfx("myprog");

dbenv.open("/database/home",
 null, Db.DB_CREATE | Db.DB_INIT_LOCK | Db.DB_INIT_MPOOL, 0);</pre></blockquote>
In the Berkeley DB 2.X release, DbEnv had accessors to obtain "managers" of type
DbTxnMgr, DbMpool, DbLog, DbTxnMgr. If you used any of these managers,
all their methods are now found directly in the DbEnv class.
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