Advanced Query optimization

Question

Hi,
I have following database model
1 table called Description with a column id (=primary key)
1 table called Names with 3 columns desc_id (foreign key to id of description), name, language
1 table called Descriptionswith 3 columns desc_id (foreign key to id of description), description, language.
All my other object have a foreign key to the primary key of description and I mapped this description object by using a DirectMapMapping (result is 2 maps with as key the language and as content the name or description).
No it seems that when I try to receive 100 objects with their name and descriptions, TopLink does 100 times a select on the descriptions and names tables (2 times 100 select statements is a really bad thing for my application performance)
I tried to solve this by using batchreading (see code attached) but this doesn't work, I do not get the descriptions and names, please help???
THX a lot
Descriptor tmp = session.getDescriptor(Descriptions.class);
          DirectMapMapping directMapMapping = new DirectMapMapping();
          directMapMapping.useMapClass(HashMap.class);
          directMapMapping.setAttributeName("name");
          directMapMapping.setReferenceTableName("NAMES");
          directMapMapping.setReferenceKeyFieldName("DESC_TID");
          directMapMapping.setDirectKeyFieldName("KEY");
          directMapMapping.setDirectFieldName("VALUE");
          directMapMapping.setKeyClass(String.class);
          directMapMapping.setValueClass(String.class);
directMapMapping.useBatchReading();
          tmp.addMapping(directMapMapping);
          directMapMapping = new DirectMapMapping();
          directMapMapping.useMapClass(HashMap.class);
          directMapMapping.setAttributeName("description");
          directMapMapping.setReferenceTableName("DESCRIPTIONS");
          directMapMapping.setReferenceKeyFieldName("DESC_TID");
          directMapMapping.setDirectKeyFieldName("KEY");
          directMapMapping.setDirectFieldName("VALUE");
          directMapMapping.setKeyClass(String.class);
          directMapMapping.setValueClass(String.class);
directMapMapping.useBatchReading();
          tmp.addMapping(directMapMapping);
          

Answer 1

Hi,
I installed the latest patch --> no result
I also removed the DirectMapMapping to make sure that this was not the problem, I replaced the 2 hashmaps by 2 classes with 2 attributes-->same problem.
I tried to use the addBatchReadAttribute but this also does not work, has anyone already used this method?
if have following mapping
Value > 1-1 > Descriptions > 1-M > Name
But we still keeps calling select statements for the latest level
I implemented it like this
ReadAllQuery query = new ReadAllQuery();
query.setReferenceClass(Value.class);
query.addBatchReadAttribute("descriptions");
Vector results = (Vector)session.executeQuery(query);
The value object has one descriptions class and each description class has multiple name and description classes. Name and description has 2 attributes: language and value
1st query is to retrievethe values --> OK
2nd for each value he does a query on the descriptions, description and name table, so 3 queries for each value
SELECT TID FROM DESCRIPTION WHERE (TID = 487)
SELECT KEY, VALUE, TID, DESC_TID FROM NAMES WHERE (DESC_TID = 487)
SELECT VALUE, KEY, TID, DESC_TID FROM DESCRIPTIONS WHERE (DESC_TID = 487)
Even when I put a non existing attribute name in the addBatchReadAttribute method, then I still does not get an error: is this method implemented or do I misuse it?
THANKS for the help