I understand the differences between optimistic and pessimistic locking*. Now could someone explain to me when I would use either one in general? And does the answer to this question change depending on whether or not I'm using a stored procedure to perform the query? *But just to check, optimistic means "don't lock the table while re...
If i SELECT a row for updating in MS SQL Server, and want to have it locked till i either update or cancel, which option is better :- 1) Use a query hint like UPDLOCK 2) Use REPEATABLE READ isolation level for the transaction 3) any other option. Thanks, Chak. ...
We are using messaging in a project of ours to implement pessimistic concurrency. This means that if messaging goes down (channel goes down), concurrency goes down. Is this done in other business applications? Do you close the application (log out the user) if messaging goes down? I'm thinking more of combining the optimistic and p...
I have read the article Locking and Concurrency in Java Persistence 2.0, and run the sample application. But i still cant realize the difference between PESSIMISTIC_READ and PESSIMISTIC_WRITE. I tried to modify the code, and where the code using PESSIMISTIC_READ and PESSIMISTIC_WRITE will have the same result that the sql will invoked wi...
Hi, We have a system in which we must use pessimistic locking in one entity. We are using hibernate, so we use LockMode.UPGRADE. However, it does not lock. The tables are InnoDB We have checked that locking works correctly in the database (5.0.32), so this bug http://bugs.mysql.com/bug.php?id=18184 seems to be no problem. We have chec...
I'm using the EclipseLink implementation of the JPA 2.0 which allows pessimistic locking. I know how to lock an entity but how do I release the lock? At first I thought this was all taken care of within a transaction (in other words, the entity is locked until you commit the transaction), but that does not seem to be the case. I tried...
Assuming I'm doing something like this (from the Active Record Querying guide) Item.transaction do i = Item.first(:lock => true) i.name = 'Jones' i.save end Is the lock automatically released at the end of the transaction? I've looked at the Active Query guide and the ActiveRecord::Locking::Pessimistic docs, and couldn't...