Advanced Queuing - Oracle

General Questions
How do you associate Oracle Parallel Server instance affinities with
queue tables?
In 8.1 you can associate OPS instance affinities with queue tables. If you are using
q1 and q2 in different instances, you can use alter_queue_table (or even create
queue table) on the queue table and set the primary_instance to the appropriate
instance_id.
Can you give me some examples of a subscriber rule containing -
message properties - message data properties.
Yes, here is a simple rule that specifies message properties - rule = 'priority 1';
here are example rules that specify a combination of message properties and data
attributes: rule = 'priority 1 AND tab.userdata.sal 1000' rule =
'((priority between 0 AND 3) OR correlation = ’BACK_ORDERS') AND
tab.userdata.customer_name like ''JOHN DOE'')'
Note that user data properties or attributes apply only to object payloads and must
be prefixed with tab.userdata in all cases. Check documentation for more examples.
Is registration for notification (OCI) the same as starting a listener?
No. Registration is an OCI client call to be used for asynchronous notifications (that
is, push). It provides a notification from the server to the client when a message is
available for dequeue. A client side function (callback) is invoked by the server
when the message is available. Registration for notification is both nonblocking and
nonpolling.
What is the use of non-persistent queues?
To provide a mechanism for notification to all users that are currently connected.
The non-persistent queue mechanism supports the enqueue of a message to a
non-persistent queue and OCI notifications are used to deliver such messages to
users that are currently registered for notification.
Is there a limit on the length of a recipient list? Or on the number of
subscribers for a particular queue?
Yes, 1024 subscribers or recipients for any queue.
How can I clean out a queue with UNDELIVERABLE messages?
You can dequeue these messages by msgid. You can find the msgid by querying
the queue table view. Eventually the messages are moved to the exception queue
Frequently Asked Questions 6-3