|Re: Persisting chained objects in CDO(MongoDB store) [message #1705226 is a reply to message #1704174]
||Thu, 13 August 2015 06:03
|| Eike Stepper
Registered: July 2009
Please note that we don't actively maintain the MongoDBStore due to the lack of resources. More comments below...
Am 07.08.2015 um 23:50 schrieb Fábio Silva:
> I am trying to persist a large emf model using CDO and mongoDB. As usual, it throws an exception saying the collection
> is too large.
Not that the document in the collection is too large?
> Then I tried to persist in chunks, but the references were lost. Ex: My model has a commit -> change -> changeRegion
That might be a bug in the MongoDBStore. IIRC the logic in there is not too complicated, so you may want to use the
debugger to investigate your problem further.
> It didn't work when I tried to persist the "commit" object, so I tried to persist changeRegion upfront. But the
> references of "change" get lost. Actually the transaction model is a bit strange. If I do the same operation, but in a
> smaller transction section, it persists in separate collections, whereas larger transaction sections leads to bigger,
> concentrated objects.
I don't understand what you mean. Perhaps it helps to be more concrete and describe the problem with an example.
Because MongoDB itself does not support proper ACID transactions across multiple documents/collections like common SQL
databases the MongoDBStore persists each CDO commit atomically in a single document. The drawback is that read access is
implemented as queries over multiple commit documents.
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