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From Aristedes Maniatis <...@maniatis.org>
Subject Re: Cayenne and transactions
Date Sun, 05 Feb 2012 12:28:58 GMT
On 5/02/12 10:11 PM, Daniel Scheibe wrote:
> Hi guys,
>
> i'm trying to figure out how Cayenne is handling transactions in regards of when data
is transferred to the database. I am trying to get some large transactions (many small records
or a few very large records) working and so far haven't had luck. If i understand correcly,
Cayenne is holding my records in a cache and when i execute the commitChanges() on the ObjectContext
it starts to transfer all of the data to the database (isolated in a real database transaction).
So my question is (and please correct me if my previuos assumption is wrong) how can I influence
on this behaviour since i pretty much need Cayenne to use the database transaction more directly.
When i skip Cayenne and issue SQL statements right through the JDBC connection (ie.g. BEGIN
TRANSACTION, UPDATE, UPDATE, UPDATE..., COMMIT TRANSACTION) it works fine as with MySQL i'm
only restricted to the maximum allowed size of the InnoDB transaction logfile which is quite
sufficient for my purposes. On the other hand
  i
> completely understand that Cayenne would not know when i've finished working with an
Entity as there is no kind of "save" command on the Entity itself.
>
> Oh, this of course only goes for storing data inside the database, not for reading.
>
> Maybe some of you guys with a bit more insight into the Cayenne internals can help me
out on this or point me to the right direction.
>
> Thanks in advance and a refreshing weekend!
>
> Cheers,
> Daniel

Can you explain a little more what you are trying to do and what problem you are trying to
avoid. Yes, there are ways to control the transactions through Cayenne (search this list for
many previous thread discussing this), but it sounds like you just need to commit your context
at the appropriate places in your code.

Ari


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Aristedes Maniatis
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