[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Transactions and locking
On Wed, 10 May 2000, Rajiv Rawal wrote:
> Hi all,
>
> I am trying to understand the Transaction and locking scheme in more detail
> in ozone. I have seen the ExtenalTransaction interface.
> When a transaction starts, i think it implicitely locks the nodes. Now what
> happens when another user tries to access a locked node. Does the user get
> an exception???. Can he still have read only access.
ozone uses pessimistic locking - multiple reads but exclusice writes.
Transactions are blocked until the object is available or a deadlock was
detected.
The native ozone API does not provide a read only mode.
Note: In contrast to RDBMS that can lock 'objects' when the transaction
starts, ozone locks objects when they are accessed. This may lead to OODBMS
like race and deadlock conditions but there is no chance to come around this
limitation.
>
> Also is there a way to explicitly set locks??
Early ozone version provided a lock() method. The current version doesn't. Why
do you need this feature.
Falko
--
______________________________________________________________________
Falko Braeutigam mailto:falko@softwarebuero.de
softwarebuero m&b (SMB) http://www.softwarebuero.de