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Posted to user@cayenne.apache.org by André Rothe <ar...@phosco.info> on 2011/01/25 14:31:23 UTC

Multiple connections per transaction

Hi,

I have seen, that Cayenne uses multiple connections per transaction (a  
DataNode can have multiple connections and it can add multiple  
connections to a transaction). I ask myself, how can Cayenne ensure  
some visibility problems, which depend on the isolation level of the  
underlying datastore? I think, you could get different results from  
different connections.

~André

Re: Multiple connections per transaction

Posted by André Rothe <ar...@phosco.info>.

Ah, okay. TransactionDataSource get always the same connection for the  
specified DataNode or creates a new one, if no connection exists. So  
you will have multiple connection within a transaction only if you  
have a transaction over multiple DataNodes.

Thank you
André

Andrus Adamchik <an...@objectstyle.org> wrote:

> Actually recent versions of Cayenne (3.0, maybe earlier) are  
> ensuring a use of a single connection per transaction.
>
> Andrus
>
> On Jan 25, 2011, at 3:31 PM, André Rothe wrote:
>
>> Hi,
>>
>> I have seen, that Cayenne uses multiple connections per transaction  
>> (a DataNode can have multiple connections and it can add multiple  
>> connections to a transaction). I ask myself, how can Cayenne ensure  
>> some visibility problems, which depend on the isolation level of  
>> the underlying datastore? I think, you could get different results  
>> from different connections.
>>
>> ~André
>>
>
>

Re: Multiple connections per transaction

Posted by Andrus Adamchik <an...@objectstyle.org>.

Actually recent versions of Cayenne (3.0, maybe earlier) are ensuring a use of a single connection per transaction.

Andrus

On Jan 25, 2011, at 3:31 PM, André Rothe wrote:

> Hi,
> 
> I have seen, that Cayenne uses multiple connections per transaction (a DataNode can have multiple connections and it can add multiple connections to a transaction). I ask myself, how can Cayenne ensure some visibility problems, which depend on the isolation level of the underlying datastore? I think, you could get different results from different connections.
> 
> ~André
>