Oracle C++ Call Interface Programmer's Guide

■ The reference to the root purchase_order object
Overview of Complex Object Retrieval
■ One or more pairs of type and depth information for customer, purchase_
order, or line_item
An application prefetching a purchase order will very likely need access to the
customer information for that purchase order. Using simple navigation, this would
require two database server accesses to retrieve the two objects.
Through complex object retrieval, customer can be prefetched when the
application pins the purchase_order object. In this case, the complex object
would consist of the purchase_order object and the customer object it
references.
In the previous example, if the application wanted to prefetch a purchase order and
the related customer information, the application would specify the purchase_
order object and indicate that customer should be followed to a depth level of
one as follows:
Ref poref;
poref.setPrefetch("CUSTOMER",1);
If the application wanted to prefetch a purchase order and all objects in the object
graph it contains, the application would specify the purchase_order object and
indicate that both customer and purchase_order should be followed to the
maximum depth level possible as follows:
Ref poref;
poref.setPrefetch("CUSTOMER", OCCI_MAX_PREFETCH_DEPTH);
poref.setPrefetch("PURCHASE_ORDER", OCCI_MAX_PREFETCH_DEPTH);
where OCCI_MAX_PREFETCH_DEPTH specifies that all objects of the specified type
reachable through references from the root object should be prefetched.
If an application wanted to prefetch a purchase order and all the line items
associated with it, the application would specify the purchase_order object and
indicate that line_items should be followed to the maximum depth level possible
as follows:
Ref poref;
poref.setPrefetch("LINE_ITEM", 1);
Object Programming 3-21