Help!! Calling PL/SQL with table of objects params

Question

Hi JDBC experts,
This is probably a familiar problem to many of you and I was hoping you can help me.
I have a JDBC application that makes calls to a PL/SQL stored procedure that accepts and returns tables (arrays) of objects. I have an equivalent representation of these in Java (the object is a simple Java class and the array of objects is a subclass of ArrayList). The object has around 10 attributes (varchar and number) and the call typically accepts and returns between 50 and 100 objects.
I noticed that converting from one representation to the other before and after the JDBC call is very time consuming. Before calling the procedure, I need to instantiate a new oracle.sql.ARRAY and fill it with oracle.sql.STRUCT equivalents for each object in my ArrayList. After the procedure call returns, I need to instantiate a new ArrayList and fill it with my Java object representation for each oracle.sql.STRUCT in the returned oracle.sql.ARRAY. Given the # of objects returned and the size of each object, this causes performance degradation.
Is there any way I can avoid the above conversion overhead? I was reading somewhere about jpub and CustomDatum. I tried it out but the code that sqlj generated looked rather complex - but if this is the recommended approach, I can follow that.
Also, are there any java code examples for dealing with table of (non-scalar) objects with CustomDatum? I saw some code for using CustomDatum with single objects but not with a table of objects.
Your help is much appreciated!
Thanks,
Niranjan

Answer 1

I would do it like this :
- use existsNode function in the filter predicate to look for candidate rows regardless of the number of occurrences of target nodes in the document
- use XPath predicates on attributes to restrict target nodes
SQL> create table temp1 of xmltype;
Table created
SQL>
SQL> insert into temp1 values(xmlparse(document
  2  '<soc id="2">
  3   <listsectii>
  4    <sectie cods="4">
  5     <prodv codp="2" cant=""></prodv>
  6    </sectie>
  7    <sectie cods="5">
  8     <prodv codp="8"></prodv>
  9    </sectie>
10    <sectie cods="6">
11     <prodv codp="2"></prodv>
12    </sectie>
13   </listsectii>
14  </soc>'));
1 row inserted
SQL>
SQL> update temp1
  2  set object_value =
  3      updateXML( object_value
  4               , '/soc/listsectii/sectie[@cods="4"]/prodv[@codp="2"]/@cant'
  5               , 'new_cant' )
  6  where existsNode( object_value
  7                  , '/soc/listsectii/sectie[@cods="4"]/prodv[@codp="2"]' ) = 1
  8  ;
1 row updated
SQL> select * from temp1;
SYS_NC_ROWINFO$
<soc id="2">
  <listsectii>
    <sectie cods="4">
      <prodv codp="2" cant="new_cant"/>
    </sectie>
    <sectie cods="5">
      <prodv codp="8"/>
    </sectie>
    <sectie cods="6">
      <prodv codp="2"/>
    </sectie>
  </listsectii>
</soc>
Of course, that implies there's already an existing "cant" attribute (not the case in your samples).
If you actually need to create one, then you must use insertChildXML() instead.