andru..bjectstyle.org schrieb am 24.04.03 21:25:53:
> BTW, Arndt, who is using Cayenne for batch processing of huge volumes of
> data, is currently working on an example application that will be included
> in the future releases of Cayenne. He will be showing exactly that - how
> to keep memory usage at bay, no matter how many rows you have to read
> through.
actually, what I'm using for high volume offline batch
is something in between the 2 extremes
(throwing away the whole context versus
using "unregisterObject" on single objects)
I use the 2 methods recently introduced in
ObjectStore:
- startTrackingNewObjects
- unregisterNewObjects
("unregisterNewObjects" just calls
"unregisterObject" on every Object
registered to the objectstore after
the call to "startTrackingNewObject")
That enables you to keep any "master data"
in memory while flushing the "volume data"
for each "commit-batch".
If you want that separation in master- and
volume-data, it requires some deeper
understanding of the constraints for the
relationship between both that are currently
documented nowhere (that's the essence
of the example I'm preparing).
But the bottomline is that you cannot
have a relationship that is navigable
from the master data to the volume-data.
regards,
Arndt
PS: the other half of the story about offline
batch processing is about prefetching batches,
where you might want to have a look in
...access.util.PrefetchHelper. But this is only
about performance, not memory-housekeeping
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