Peter is right in his assessment that DataContext would cache all its
loaded objects (especially since they get in a dirty state via
'deleteObject'). To solve this problem, you may use a loop counter
and commit and throw away the DataContext every X iterations (e.g.
every 1000 or so). This will clear the memory.
On top of that, if you want all 800000 deletes to be processed as a
single transaction, you may do the above, but also wrap that code in
a manual transaction:
http://cayenne.apache.org/doc/understanding-transactions.html
Andrus
On Mar 6, 2007, at 6:51 PM, Peter Schröder wrote:
i experienced the same problem. i thinks this was because of using
objectFromDataRow()
which puts the object into the dataRow-cache and will result in out-
of-memory errors.
as a workaround i used the raw-object/data-row object from the query.
-----Ursprüngliche Nachricht-----
Von: marco turchi [mailto:[EMAIL PROTECTED]
Gesendet: Dienstag, 6. März 2007 17:48
An: [email protected]
Betreff: out of memory
Dear experts,
I run a code, where I read 800.000 records from a database, but what I
obtain is the error "out of memory: heap....".
I use the following cayenne commands:
Expression exp_date = Expression.fromString("dateRetrieval >=
$start_d and dateRetrieval < $end_d and type=$type");//("type=$type");
Map parameters =new HashMap();
parameters.put("end_d", "2006-03-09" );
parameters.put("start_d", "2005-10-07" );
parameters.put("type", "Job");
exp_date = exp_date.expWithParameters(parameters);
final SelectQuery feedsquery = new SelectQuery(FeedsAll.class,
exp_date);
int count=0;
try{
final ResultIterator it_q = context.performIteratedQuery
(feedsquery);
while(it_q.hasNextRow()){
final Map row = it_q.nextDataRow();
final FeedsAll obj = (FeedsAll)
context.objectFromDataRow(FeedsAll.class, new DataRow(row), true);
.....
context.deleteObject(obj);
}
}
catch(Exception e){
//System.out.println("Fatal Error: "+e);
log.error("Fatal Error: ",e);
log.info(e.getStackTrace());
}
what is it wrong? I understood that using the performIteratedQuery, I
could read a huge number of records without memory problem.
Can you help me?
Thanks a lot
Marco
