XA transactions and state information

[Mamta Satoor]

Hi,

 

From Dan's explanation on Derby-421 (starting an XA transaction resets the isolation level set with SET CURRENT ISOLATION) about various transaction states, what I understand is that local transaction and global transaction have to maintain their own states. I wrote a simple test program to check this behavior and it seems like Derby is not doing so.

 

My test program gets a XA connection which is part of the local transaction. Derby's default isolation level is CS and that is what the connection object has at this point. I change the isolation level to UR within the local transaction. Now, the XA connection joins a global transaction. I had expected that the isolation level of the connection inside the global transaction would be the default isolation level CS but that is not the case, instead, it is set to the isolation level UR which is what the local transaction had it. Within the global transaction, I change the isolation level to RS and then exit the global transaction so the connection is now attached to the local transaction. The isolation level at this point is set to RS rather than UR. This seems incorrect. Any comments?

 

Following is the code snippet

  EmbeddedXADataSource dscsx = new EmbeddedXADataSource();
  dscsx.setDatabaseName("c:/dellater/db1");
  XADataSource dsx = dscsx;
  XAConnection xac = dsx.getXAConnection();
  con = xac.getConnection ();
  s = con.createStatement();
  System.out.println("default isolation level should be CS? " + con.getTransactionIsolation());
  dumpRS(s.executeQuery("VALUES CURRENT ISOLATION"));
  System.out.println ("change the isolation level with setTransactionIsolation");
  con.setTransactionIsolation(Connection.TRANSACTION_READ_UNCOMMITTED);
  System.out.println("new isolation level should be UR? " + con.getTransactionIsolation ());
  dumpRS(s.executeQuery("VALUES CURRENT ISOLATION"));

  XAResource xar = xac.getXAResource();
  Xid xid = new cdsXid(1, (byte) 35, (byte) 47);
  xar.start(xid, XAResource.TMNOFLAGS);

  s = con.createStatement();
  System.out.println("isolation level inside global transaction is " + con.getTransactionIsolation());
  dumpRS(s.executeQuery("VALUES CURRENT ISOLATION"));
   System.out.println("change the isolation level inside global transaction with setTransactionIsolation");
  con.setTransactionIsolation(Connection.TRANSACTION_REPEATABLE_READ);
  System.out.println("new isolation level should be RS? " + con.getTransactionIsolation());
  dumpRS(s.executeQuery("VALUES CURRENT ISOLATION"));

  xar.end(xid, XAResource.TMSUCCESS);
  xar.rollback(xid);

  System.out.println("isolation level outside global transaction should be UR? " + con.getTransactionIsolation());
  dumpRS(s.executeQuery("VALUES CURRENT ISOLATION"));

thanks,

Mamta