hi andreas,
i opened an issue in jira http://issues.apache.org/jira/browse/OJB-22
jakob
Jakob Braeuchi schrieb:
hi andreas,
ojb selects all columns but creates proxies instead of fully materialized Article objects.
what related object do you want to prefetch here ?
jakob
Andreas Bohnert schrieb:
hi,
may someone can help me with the proxies, please!
everything works fine, prefetching works as it should, but when OJB initially selects the oid's, it does select all fields instead of just the pk!
let's say, there is a table 'Article' with 200 000 objects.
I have written an Article Class, an ArticleProxy and an ArticleInterface. The proxy is configured in the repository_user.xml like this:
<class-descriptor class="at.wb.Article" proxy="at.wb.ArticleProxy" proxy-prefetching-limit="100" table="article" > <field-descriptor id="0" name="articleId" column="articleId" jdbc-type="INTEGER" primarykey="true" autoincrement="true" /> <field-descriptor id="4" name="data" <-- big! column="data" jdbc-type="VARBINARY" /> </class-descriptor>
When I select the Article table I use a CollectionByQuery.
Criteria crit = new Criteria();
crit.addEqualTo(...
crit.addEqualTo(...
QueryByCriteria q = new QueryByCriteria( Article.class, crit );
q.addOrderBy("articleId", true);
col = broker.getCollectionByQuery(query);
When I look at the sql statement, I can see, that OJB selects ALL fields (in this case articleId and data ) instead of just the primary key!
I get a huge memory usage because of this select, and it seems, that this is because of the 'data' field, which is very big.
to get around this, I select the oid's with a ReportQuery, and build the proxies like this:
List oids = getReportQueryList(q);
RemovalAwareCollection rows = new RemovalAwareCollection();
for (Iterator it = oids.iterator(); it.hasNext(); ) {
Object[] row = (Object[]) it.next();
Integer oid = (Integer) row[0];
rows.add( VirtualProxy.createProxy( broker.getPBKey(), ArticleProxy.class,
new Identity( Article.class, Article.class, row) )); }
this works fine, but the prefetching does not work anymore! when I access a getter, I get the data objects one by one.
what's wrong with this??
thanks for your help, andreas
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