Advanced Queuing - Oracle

General Questions
Message retention means the messages are there, but how does the
subscriber access these messages?
Typically we expect the subscriber to access the messages using the dequeue
interface. If, however, you would like to see processed or waiting messages, you can
either dequeue by message id or use SQL.
Can the sort order be changed after the queue table is created?
You cannot change the sort order for messages after you have created the queue
table.
How do I dequeue from an exception queue?
The exception queue for a multiconsumer queue must also be a multiconsumer
queue.
Expired messages in multiconsumer queues cannot be dequeued by the intended
recipients of the message. However, they can be dequeued in the REMOVE mode
once (only once) using a NULL consumer name in dequeue options. Messages can
also be dequeued from an exception queue by specifying the message ID.
Expired messages can be dequeued only by specifying message ID if the
multiconsumer exception queue was created in a queue table without the
compatible parameter or with the compatible parameter set to '8.0'
What does the latency parameter mean in scheduling propagation?
If a latency less than 0 was specified in the propagation schedule, the job is
rescheduled to run after the specified latency. The time at which the job actually
runs depends on other factors, such as the number of ready jobs and the number of
job_queue_processes. It may also be affected by the value for job_queue_
interval. Please refer to the MANAGING JOB QUEUES chapter of the Oracle9i
Database Administrator’s Guide for more information on job queues and SNP
background processes.
How can I control the tablespaces in which the queue tables are
created?
You can pick a tablespace for storing the queue table and all its ancillary objects
using the storage_clause parameter in DBMS_AQADM.CREATE_QUEUE_TABLE.
However, once you pick the tablespace, all IOTs and indexes created for that queue
table will go to the specified tablespace. Currently, you do not have a choice to split
them between different tablespaces.
6-2 Oracle9i Application Developer’s Guide - Advanced Queuing