db4o Developer Community

I am learning db4o and like it a lot.
Obviously I testing performance. And I do have a problem with the following.

I am using SODA.

My database contains 2 000 Products, 30 100 Customers and 300 100 Orders.
An Order contains a reference to a Product instance and a Customer Instance.

I have one index on Customer.LastName, Order.Amount and Product.Name.

To make myself clear I will use the SQL metaphore.

The following query run in 0.15s
 
    SELECT * FROM 'Order'
    WHERE
        Amount = '9560.333333333333333333333333'

Bit the following query run in 5s

    SELECT * FROM 'Order'
    WHERE
        Amount = '9560.333333333333333333333333' and
        Customer.LastName = 'Colette U.1'

Here I am referencing the property LastName from the Customer instance referenced by the Order instance.
 

Here is my C# code

    IQuery          query   = cm._db.Query();
    query.Constrain(typeof(db4oMSE.TestClasses.Order));

    IConstraint C1 = query.Descend("Amount").Constrain(9560.333333333333333333333333M);
    IConstraint C2 = query.Descend("Customer").Descend("LastName").Constrain("Colette U.1");
    C2.And(C1);
    Db4objects.Db4o.IObjectSet ResultSet = query.Execute();


What is the right way to write this kind of query ?

How do we make it faster ?

    With a relational database this kind of query with a inner join with the right indexes would not take 5 seconds.

Thanks.

You have to set an index to the customer field, too.

If you use single references to other objects you have to set an index on this field.

mfg Origon