Some of the JDO providers (such as KODO) provide a feature that auto-left joins
wherever possible. This would be very nice for JBoss to have. Basically, here's
what I'm looking for.
A switch should allow Jboss to auto-left join along each CMR relationship
provided that the following two conditions are true....
1) This is a single element relationship, we won't be pulling back a set.
2) This relationship references a class that hasn not yet been referenced (so
there are no loops).
Given that these two conditions are met, the resulting group of left joins
wouldn't return any more rows than other wise, and it could eliminate the need
for a lot of database trips.
Is there any global option that can enable this sort of thing?
In addition, slightly unrelated, I have this for my defaults....
java:/DataWarehouseDS
<datasource-mapping>Oracle9i</datasource-mapping>
<create-table>true</create-table>
<remove-table>false</remove-table>
<read-only>false</read-only>
<row-locking>false</row-locking>
<pk-constraint>true</pk-constraint>
<fk-constraint>false</fk-constraint>
<preferred-relation-mapping>foreign-key</preferred-relation-mapping>
<read-ahead>
on-find
<page-size>1000</page-size>
<eager-load-group>*</eager-load-group>
<!--deep-read-ahead /-->
</read-ahead>
The problem is that the read-ahead isn't appearing to work. We grab all the
data on-find, like this.....
SELECT t0_o.id, t0_o.name, t0_o.indx FROM risk_reader.ETF_VIEW t0_o
This code is executed once, so far so good.
Then when I loop through the etfs to grab their data, I get a sql statement per
ETF, like this...
SELECT name, indx FROM risk_reader.ETF_VIEW WHERE (id=?)
This shouldn't happen, as I just fetched this data with the on-find query,
right? This is using COmmit option A, so this should be in the cache already.
Thanks
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