Implicit autocommit?

I am using postgresql-8.1-408.jdbc3.jar w/ PostgreSQL 8.1.8 on Kubuntu
Linux.

Given the following testcase (note autocommit is disabled)...

--------- BEGIN SOURCE -----------
import java.sql.*;

public class VacuumTest
{
public static void main(String[] args)
throws SQLException
{
Connection conn = null;
try
{
Class.forName("org.postgresql.Driver");
conn =
DriverManager.getConnection("jdbc:postgresql://localhost/test");
conn.setAutoCommit(false);

update(conn, "create temp table tt1 (c1 int4)");
update(conn, "vacuum tt1");
update(conn, "drop table tt1");
}
catch (Exception exc)
{
exc.printStackTrace();
}
finally
{
if (conn != null)
{
conn.close();
}
}
}

private static void update(Connection conn, String sql)
throws SQLException
{
Statement stmt = conn.createStatement();
try
{
stmt.executeUpdate(sql);
}
finally
{
stmt.close();
}
}
}
---------- END SOURCE ------------

...I see the following result:

org.postgresql.util.PSQLException: ERROR: VACUUM cannot run inside a
transaction block
at
org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:1531)
at
org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1313)
at
org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:188)
at
org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:452)
at
org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:340)
at
org.postgresql.jdbc2.AbstractJdbc2Statement.executeUpdate(AbstractJdbc2Statement.java:286)
at VacuumTest.update(VacuumTest.java:38)
at VacuumTest.main(VacuumTest.java:16)

I debugged into the driver and found it was issuing a "BEGIN" to the
backend just before each statement. Why would it do this with
autocommit disabled?

Thanks,
Eric Faulhaber