Large database force use of recordset

[Edson Carlos Ericksson Richter <ed...@mgrinformatica.com.br>]

Hi!

I'm using a large database to make some reporting.
The problem is when I need to show a report with about 100000 records. This just freeze my machinery, and after 10 minutes, I get OutOfMemoryException...

Yes, I know that I should use java -Xmx 128M -Xms 64M and so on, so I'll get things working.

But one developer at my side show me that is possible to get same 100000 records shown in about 2 minutes just with default values for Xmx and Xms.

Well, I needed to put my mind to work, and adapted my ReportBuilder to accept a Collection returned by OJB or a ResultSet, and now I need to obtain:

1) A Connection from OJB, and the formed query (the SELECT that OJB is generating to execute), so I can execute and pass the ResultSet to the report builder; OR
2) A ResultSet obtained after execution by OJB, and before OJB build the objects (to me, it's the ideal because I don't need to worry about statements and so on).

Some one has tips on how to do this?

Thanks,


Edson Richter


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Problem storing a collection.

[Michael Becke <be...@u.washington.edu>]

I am experiencing a problem when I try to store an object that contains 
a collection.  It seems that I am only able to create and add one object 
to the collection at a time.  Here are the details of my setup:

	OJB cvs snapshot from yesterday (Aug 11)
	WebSphere 4.0.5
	DB2 7.2.6
	
The repository for the classes in question look like the following, with 
unnecessary details removed.

    <class-descriptor
    	  class="Child"
    	  table="SCHEMA.CHILD">
       <field-descriptor
          name="id"
          column="ID"
          jdbc-type="INTEGER"
          primarykey="true"
          autoincrement="true"
          access="readonly"
       />
       <field-descriptor
          name="parentId"
          column="PARENT_ID"
          jdbc-type="INTEGER"
       />
    </class-descriptor>

    <class-descriptor
    	  class="Parent"
    	  table="SCHEMA.PARENT">
       <field-descriptor
          name="id"
          column="ID"
          jdbc-type="INTEGER"
          primarykey="true"
          autoincrement="true"
          access="readonly"
       />
       <collection-descriptor
          name="children"
          auto-retrieve="true"
          auto-update="false"
          auto-delete="false"
          element-class-ref="Child">
          <inverse-foreignkey field-ref="parentId"/>
       </collection-descriptor>
    </class-descriptor>

I am using DB2 identity fields for the object IDs for both of these 
classes.  Yes, I know this is not popular, but such is life.  To support 
this I am using the SequenceManagerNativeImpl (modded to remove 
setReferenceFKs() as this does not seem to work properly).

My code looks like the following:

	// the parent has already been saved and has a valid ID
         Parent parent = someparent;

         Transaction transaction = odmg.currentTransaction();
         transaction.lock(parent, Transaction.WRITE);

	Child child1 = new Child();
	child1.setParentId(parent.getId());
	parent.addChild(child1);
         transaction.lock(child1, Transaction.WRITE);

	Child child2 = new Child();
	child2.setParentId(parent.getId());
	parent.addChild(child2);
         transaction.lock(child2, Transaction.WRITE);

After this I commit the transaction but only the first child is stored.

Any thoughts?

Thanks,

Mike




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