Thanks Andy for these information.
Regarding the Location.mem() method I have noticed that it does not
create internally a new "mem location object" each time the method is
called. Thus, if I create several instances of StoreConnection in a
JVM by using Location.mem() as parameter, all the StoreConnections
will share the same location. Is it not possible to create a unique
memory location each a call to Location.mem() is performed? This would
be very useful to reproduce what is possible with new
Location("/unique/path/").
Kind Regards,
Laurent
On Sun, Oct 30, 2011 at 6:05 PM, Andy Seaborne <[email protected]> wrote:
> On 29/10/11 15:06, Laurent Pellegrino wrote:
>>
>> Hi all,
>>
>> I have several questions about how to use the new transaction features
>> provided with the last version of TDB:
>>
>> * Do we have to use the commit operation with a read transaction? Is
>> it compulsory (e.g. to release a lock), optional, or an error?
>
> If you are using transaction at all, then you must use a read tranaction (it
> can end with commit, abort or close - it'll make no difference for read).
>
> Locking is not needed except that each transaction must be single threaded
> (basically, multiple-reader OR single-writer applies within a transaction
> but only one thread per transaction is tested; no guarantees multiple
> threads per transaction will everr be supported ; they just "should" work at
> the moment).
>
>> * It seems that operations on DatasetGraphTxn do not throw checked
>> exceptions. However, do these operations can throw an unchecked
>> exception?
>
> Yes.
>
> But any exception is a sign of internal problems (or breaching concurrency).
>
> No normal operation should throw an exception.
>
>> * Does nested read transactions are allowed?
>
> No. No nested trasnactions at all. But if you are in a read transaction
> you can make as many reads as you want.
>
>> * When a StoreConnection is created with Location.mem() as location,
>> what is created in memory (dataset+journal, only dataset or only
>> journal)?
>
> Everything is (should) be in-memory.
>
> It's for testing only.
>
>> * Does the information on the following webpages are up to date?
>> - http://openjena.org/wiki/TDB/Transactions
>
> Should be.
>
>
>> - https://cwiki.apache.org/confluence/display/JENA/TxTDB-design
>
> May be not.
> That was the design and no design survives first contact with implementation
> reality
>
> Andy
>
>>
>> Kind Regards,
>> Laurent
>
>
