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<title>Berkeley DB Reference Guide: Release 3.0: the Db class for C++ and Java</title>
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<td><h3><dl><dt>Berkeley DB Reference Guide:<dd>Upgrading Berkeley DB Applications</dl></h3></td>
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<h1 align=center>Release 3.0: the Db class for C++ and Java</h1>
<p>The static Db::open method and the DbInfo class have been removed in the
Berkeley DB 3.0 release. The way to open a database file is to use the new Db
constructor with two arguments, followed by set_XXX methods to configure
the Db object, and finally a call to the new (nonstatic) Db::open(). In
comparing the Berkeley DB 3.0 release open method with the 2.X static open
method, the second argument is new. It is a database name, which can
be null. The DbEnv argument has been removed, as the environment is now
specified in the constructor. The open method no longer returns a Db,
since it operates on one.
<p>Here's a C++ example opening a Berkeley DB database using the 2.X interface:
<p><blockquote><pre>// Note: by default, errors are thrown as exceptions
Db *table;
Db::open("lookup.db", DB_BTREE, DB_CREATE, 0644, dbenv, 0, &table);</pre></blockquote>
<p>In the Berkeley DB 3.0 release, this code would be written as:
<p><blockquote><pre>// Note: by default, errors are thrown as exceptions
Db *table = new Db(dbenv, 0);
table->open("lookup.db", NULL, DB_BTREE, DB_CREATE, 0644);</pre></blockquote>
<p>Here's a Java example opening a Berkeley DB database using the 2.X interface:
<p><blockquote><pre>// Note: errors are thrown as exceptions
Db table = Db.open("lookup.db", Db.DB_BTREE, Db.DB_CREATE, 0644, dbenv, 0);</pre></blockquote>
<p>In the Berkeley DB 3.0 release, this code would be written as:
<p><blockquote><pre>// Note: errors are thrown as exceptions
Db table = new Db(dbenv, 0);
table.open("lookup.db", null, Db.DB_BTREE, Db.DB_CREATE, 0644);</pre></blockquote>
<p>Note that if the dbenv argument is null, the database will not exist
within an environment.
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