Hi guys,
I found this really cool bug dealing with Orion Server 1.5.2 and
IBM DB2's JDBC implementation. I don't know if it's
a) me (likely)
b) orion (perhaps)
c) ibm's jdbc implementation (wouldn't doubt it)
I BCC'ed a IBM dude, so for his info, orion server is found
at www.orionserver.com
but here it goes...
Remember that transaction problem I had? Well I solved it. I'm
going to include some messy source code because I want to make sure
the problem has the best chance of being replicated... but of
course there might be differing opinions. ;)
The bug is this. I set autocommit to false... but then I update
this table:
create table lim (cap int);
insert into lim values (600);
Then I run this program which increments the value of cap by 10,
then rolls it back. If I include the statement:
DatabaseMetaData dbmd = conn.getMetaData();
** and/or the statement **
out.println ("isolation: " + conn.getTransactionIsolation());
In my code... it seems to turn autocommit back on. If I throw that
statement back into the comment section, things work fine again.
Neat isn't it?
Now can any one tell me where the problem might lie? I mean it's
cool if you can't... but it should be noted for future reference
should you run into the same problem as I have.
Alright then, enjoy the code...
Jeff
Here goes...
import java.util.Map;
import java.util.Hashtable;
import java.io.PrintWriter;
import java.io.IOException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletException;
import javax.naming.InitialContext;
import javax.rmi.PortableRemoteObject;
import java.sql.*;
import javax.sql.DataSource;
public class XTest extends HttpServlet {
public void doPost (HttpServletRequest req, HttpServletResponse
res)
throws ServletException, IOException
{
log ("Start XTest");
PrintWriter out = res.getWriter();
out.println ("XTest start");
out.println ("here we go...");
Connection conn = null;
try {
InitialContext ctx = new InitialContext();
DataSource ds = (DataSource) ctx.lookup
("jdbc/THEDS");
conn = ds.getConnection();
/*
DatabaseMetaData dbmd = conn.getMetaData();
out.println ("isolation: " +
conn.getTransactionIsolatio
n());
out.println ("tx_none: " +
Connection.TRANSACTION_NONE);
if
(dbmd.supportsTransactionIsolationLevel(Connection.TR
ANSACTION_NONE)) out.println ("Supports TX_none");
else out.println ("NO suuport for TX_NONE");
out.println ("tx_rd_com: " +
Connection.TRANSACTION_READ
_COMMITTED);
if
(dbmd.supportsTransactionIsolationLevel(Connection.TR
ANSACTION_READ_COMMITTED)) out.println ("Supports TX_rd_com");
out.println ("tx_rd_uncom: " +
Connection.TRANSACTION_RE
AD_UNCOMMITTED);
if
(dbmd.supportsTransactionIsolationLevel(Connection.TR
ANSACTION_READ_UNCOMMITTED)) out.println ("Supports TX_rd_uncom");
out.println ("tx_rpt_rd: " +
Connection.TRANSACTION_REPE
ATABLE_READ);
if
(dbmd.supportsTransactionIsolationLevel(Connection.TR
ANSACTION_REPEATABLE_READ)) out.println ("Supports TX_rpt_rd");
out.println ("tx_ser: " +
Connection.TRANSACTION_SERIALI
ZABLE);
if
(dbmd.supportsTransactionIsolationLevel(Connection.TR
ANSACTION_SERIALIZABLE)) out.println ("Supports TX_ser");
*/
try {
conn.setAutoCommit (false);
} catch (Exception e) {
out.println ("setAC no workie");
}
if (conn.getAutoCommit()) {
out.println ("crap it's autocommiting");
} else {
out.println ("it's claiming no auto ");
}
PreparedStatement ps = conn.prepareStatement
("update lim set cap = cap + 10 ");
int n = ps.executeUpdate ();
conn.rollback();
out.println ("yeah ok" + n + "changes");
/*
int done = 0;
ps = conn.prepareStatement
("select * from flag");
//ps.setQueryTimeout (60);
while (done == 0)
{
ResultSet rs = ps.executeQuery();
while (rs.next())
{
if (rs.getInt("cap") == 666)
{
out.println ("rollback" + n +
"changes")
;
conn.rollback();
done = 1;
break;
}
if (rs.getInt("cap") == 777)
{
//out.println ("commit" + n +
"changes")
;
out.println ("rollback" + n +
"changes")
;
//conn.commit();
conn.rollback();
done = 1;
break;
}
}
}
*/
ps = conn.prepareStatement ("select * from
lim");
ResultSet rs = ps.executeQuery();
rs.next();
out.println ("lim: "+rs.getString("cap"));
ps = conn.prepareStatement ("select * from
flag");
rs = ps.executeQuery();
rs.next();
out.println ("flag: "+rs.getString("cap"));
conn.close();
} catch (Exception e) {
out.println ("not ok");
out.println ("try: " + e.getMessage());
try {
conn.rollback();
conn.close();
} catch (SQLException se) {
out.println ("can't rollback or close"
+ e.getMessage());
}
}
}
public void doGet (HttpServletRequest req, HttpServletResponse
res)
throws ServletException, IOException
{
doPost (req, res);
}
}
