Oracle Superior Queue: A Information – DZone – Uplaza

On this article, we’ll take a look at what Oracle superior queue is, discover a number of the use circumstances, and think about widespread finest practices whereas implementing queue.

Transient Overview of Oracle Superior Queue (AQ)

In a enterprise software, many techniques and apps work collectively to combine and trade data. Oracle Superior Queuing permits asynchronous communication by sending and receiving the message. This permits the message to be seamlessly built-in and saved on the database construction stage. 

Excessive availability, scalability, and reliability are all operational advantages of Oracle Superior Queuing. As the data is saved on the database stage DBAs and builders have full management over the message and its life cycle.

Significance of Messaging Techniques in Enterprise Functions

Enterprise apps are sometimes massive and complex packages which can be distinctive to the group. This requires a excessive diploma of safety and scalability. Usually, in-house and externally acquired merchandise trade data with one another to attain the meant enterprise goal. Oracle Superior queue permits the message to be propagated in a dependable and safe method, because it inherits the messaging requirements, messages are by no means misplaced, because the messages are saved on the native database stage.  This notably turns out to be useful, when the apps talk exterior of a company’s community to trade and retailer the data. 

Article Goals and Scope

This text goals to understand the idea of Oracle Superior Queuing, its benefits, and the strategy to its implementation. Upon finishing this text, the reader needs to be outfitted to grasp, apply, and convey some great benefits of Oracle Superior Queuing.

What Is Oracle Superior Queue?

Oracle Superior Queuing (AQ) is a message-oriented middleware that’s built-in into Oracle Database. It makes use of the capabilities of the Oracle database to maintain messages in persistent queues. It’s primarily designed for managing software processes, dealing with small providers, and executing actions in response to particular occasions. 

Historical past of Oracle AQ

• Oracle first included a sophisticated queue as a built-in function in launch 8i.
• Oracle 9i additional enhanced AQ by bettering efficiency, message expiration upkeep, and prioritizing messages within the queue.
• XML message assist, message transformation, and monitoring options had been all included in Oracle 10g.
• Multitenant structure and safety features had been enhanced in Oracle 12c

Key Options and Advantages of Oracle AQ

In a nutshell, excessive availability, scalability, reliability, and traceability are the principle options of queue knowledge. We are going to take a look at these options in depth:

• Oracle queues have been engineered to be each scalable and extremely performant, enabling it to successfully handle large message volumes (CLOB/ RAW knowledge) and facilitate concurrent message processing. It makes use of parallel processing and partitioning, two scalability options of Oracle Database, to fulfill the calls for of demanding enterprise environments.
• AQ queue messages are reliable and long-lasting. As a result of they’re saved within the database, even within the case of system crashes or failures, they don’t seem to be misplaced. For mission-critical purposes the place knowledge integrity is important, this dependability is crucial.
• It permits messages to be exchanged between purposes or between completely different areas of an software with out requiring each events to be obtainable or actively current on the identical time.
• AQ provides the flexibility to keep up message ordering inside a queue, guaranteeing that messages are dealt with within the order that they’re queued. For purposes the place a exact order of operations is required, this function is essential (FIFO – First In First Out).
• Oracle’s superior queue can deal with a variety of message varieties, reminiscent of textual content, XML, uncooked knowledge, and user-defined varieties. Due to this adaptability, builders can combine AQ with a wide range of software architectures and work with a wide range of knowledge varieties.
• Messages may be assigned various ranges of precedence because of AQ’s assist for priority-based message queuing. Due to this function, advanced message processing logic based mostly on message precedence may be applied.
• Monitoring and administration: By means of Oracle Enterprise Supervisor (OEM), various database views, and APIs, AQ provides intensive monitoring and administration capabilities. Builders can simply handle queue configurations, monitor message processing metrics, and regulate queue standing.
• AQ is engineered to be each scalable and extremely performant, enabling it to successfully handle large message volumes and facilitate concurrent message processing. It makes use of parallel processing and partitioning, two scalability options of Oracle Database, to fulfill the calls for of demanding enterprise environments.

Comparability With Different Messaging Techniques (e.g., JMS, MSMQ)

There are different comparable messaging platforms obtainable within the Market particularly JMS (Jave Messaging System and Microsoft Message Queue). As a matter of comparability, we’ll see the first variations between them. This shall assist architects and builders in choosing or recommending probably the most right platform.

Message Mannequin clarification through diagram

Deciding on between Oracle AQ, JMS, and MSMQ relies on the corporate’s present expertise framework, the necessity for scalability, the setting for deployment, and the anticipated want for future integration. Each messaging answer provides distinctive benefits and is acceptable for varied conditions, contemplating these components.

Structure and Elements

Up to now, we’ve understood, what’s oracle AQ, its historical past, advantages, and a comparability with comparable messaging techniques or platforms. From right here onwards, we’ll take a deep dive into Oracle AQ structure and parts.

Oracle AQ Structure Overview

Now let’s see a high-level Oracle AQ architectural diagram.

Right here, the supply software enqueues the messages, which Oracle AQ reads. As subscribers are registered the messages are dequeued into the goal software

In response to the dequeued messages, the goal software might or might not ship the response/acknowledgment again to the supply software. Within the occasion of response messages, the goal software sends the response to Oracle AQ by enqueuing the message in AQ and the supply software dequeues the message to know the response on the goal system. 

Be aware: Affected queues should be to register and subscribe to have the ability to ship and obtain the messages. Beneath the AQ Elements matter, we’ll see how queues may be registered and subscribed. 

Now, let’s take one use case of Oracle AQ to have a greater understanding and the way it works.

Now we’ll see, what’s inside Oracle AQ.

In Oracle AQ we primarily have queues, queue tables, message processing, and propagation. Right here, exception queues are maintained to deal with any failover circumstances. 

Additionally, you’ll discover that automated propagation may be set which permits the messages may be transmitted from one database to a different queue in the identical or completely different database. That is notably, helpful for distributed purposes that are coping with a number of techniques. Within the subsequent chapter we’ll see what core AQ parts are.

AQ Elements

As seen within the above diagram (architectural overview), the first parts of Oracle AQ are:

• Queue: Logical container for the payloads, A number of queues may be created based mostly on the appliance necessities.
• Tables: Tables particularly designed for storing the payloads and metadata.
• Message: It’s precise knowledge transmitted by way of the queue; they sometimes have the data required for its consumption within the software.
• Subscriber: Subscribers should be set to devour the messages obtainable within the queue. It may be an Oracle set off or a process.

Creating and Configuring Superior Queues

Earlier than creating queues, queue tables have to be created. For a similar, you could must work with the native DBA. DBA might must outline queue tables and handle permissions. To create queue tables, execute the under pattern SQL assertion.

CREATE TABLE my_queue_table(

    queue_column1   datatype,

    queue_column2   datatype,

    ... );

CREATE TABLE my_queue (

    id     NUMBER,

   some_data   VARCHAR2(100)

);

As soon as, queue tables are created, proceed with the creation of queues. Execute under SQL block under.

Be aware: The queue itself is a logical container for messages of a selected sort.

BEGIN
    DBMS_AQADM.CREATE_QUEUE (
        queue_name     => 'queue_name',
        queue_table    => 'my_queue_table',
        queue_type     => 'NORMAL_QUEUE'
    );
END;

As soon as queues are created, grants have to be given to it, in order that, the required consumer(s) can have entry to it.

GRANT EXECUTE ON dbms_aqadm TO myuser;
GRANT EXECUTE ON dbms_aq TO myuser;
GRANT ENQUEUE, DEQUEUE ON my_queue TO myuser;

Enqueuing and Dequeuing Messages

Earlier than enqueuing or dequeuing the message, one should register and subscribe to the queues. After grants, ensure that the subscriber for the queue has been registered in order that the message may be enqueued or dequeued. Check with the SQL block under.

Choose rely(1) into w_subscr from dba_queue_subscription
The place queue_name = ‘my_queue’ and consumer_name = ‘udf_consumber’;
If (w_subscr  ‘my_queue’
    consumer_name = >‘udf_consumber );
Finish If;
Choose rely(1) into w_subscr_registrations from dba_subscr_registrations
The place subscription_name = ‘my_queue: udf_consumber’;
If (w_subscr_registrations = 0) Then
Dbms_aq.register( sys.aq$_reg_info_list(
           sys.aq$_reg_info(
             identify      => 'my_queue: udf_consumbe',
             namespace =>  dbms_aq.namespace_aq,
             callback  => 'plsql://calling_trigger_to_setup_func_or_proc',
             context   =>  NULL)       ),       1);  
Finish If;

As soon as queues are registered and subscribed, let’s examine how the message may be enqueued or dequeued.

DECLARE
    enqueue_options  DBMS_AQ.ENQUEUE_OPTIONS_T;
    message_properties  DBMS_AQ.MESSAGE_PROPERTIES_T;
    message_handle  RAW(16);
BEGIN
    DBMS_AQ.ENQUEUE (
        queue_name         => 'my_queue',
        enqueue_options    => enqueue_options,
        message_properties => message_properties,
        payload            => 'That is my first AQ message',
        msgid              => message_handle
    );
    COMMIT;
END;

It will enqueue the message “This is my first AQ message” within the queue ‘my_queue’ Now, let’s examine how messages are dequeued. Be aware the block.

'plsql://calling_trigger_to_setup_func_or_proc'

Ought to name the code under.

DECLARE
    dequeue_options  DBMS_AQ.DEQUEUE_OPTIONS_T;
    message_properties  DBMS_AQ.MESSAGE_PROPERTIES_T;
    message_handle  RAW(16);
    message_payload VARCHAR2(4000);
BEGIN
    DBMS_AQ.DEQUEUE (
        queue_name         => 'my_queue',
        dequeue_options    => dequeue_options,
        message_properties => message_properties,
        payload            => message_payload,
        msgid              => message_handle
    );
    DBMS_OUTPUT.PUT_LINE('Message dequeued: ' || message_payload);
    COMMIT;
END;

Be aware: the payload messages are queued and saved in my_queue_table and see that COMMIT assertion is vital to maneuver to the following message(s). 

Superior Queue Options

Message Prioritization and Scheduling

Oracle Superior Queuing (AQ) offers you management over the timing and means messages are dealt with inside a queue by providing various instruments that facilitate scheduling and message prioritizing.

You may give messages in a queue various levels of urgency or precedence by utilizing message prioritizing. Prioritization using message properties is supported by Oracle AQ.

Pattern SQL Block to set message precedence:

message_properties  DBMS_AQ.MESSAGE_PROPERTIES_T;
message_properties.precedence := 1;  -- Set the precedence of the message

Equally, for the messages to be dequeue, we are able to set a precedence/order by:

dequeue_options DBMS_AQ.DEQUEUE_OPTIONS_T;
dequeue_options.navigation := DBMS_AQ.FIRST_MESSAGE;

Message scheduling permits you to delay the supply of messages till a specified time or to schedule recurring deliveries of messages. That is achieved utilizing the enqueue_time attribute within the message properties.

enqueue_time TIMESTAMP := SYSTIMESTAMP - 1;

Message Grouping and Batching

Message grouping and batching are notably helpful once we wish to optimize and enhance efficiency. Group may be created on the time of queue creation. Messages belonging to 1 queue may be grouped to kind a set that may solely be consumed by one consumer at a time. This requires that the queue be created in a queue desk that’s enabled for transactional message grouping. This helps in categorizing messages based mostly on enterprise logic or processing necessities.

Each message in a bunch has a bunch or message ID and sequence quantity. To determine the message as belonging to which group or message. A set of messages that may solely be seen by one consumer at a time may be created by grouping messages from the identical queue. To perform this, the queue have to be established in a queue desk with transactional message grouping enabled. 

To know this, let’s assume, you may have a number of exterior knowledge suppliers for comparable knowledge factors. You’ll be able to group them in a distinct queue desk. It will assist to trace and hint the messages obtained from the completely different knowledge suppliers and act accordingly.

Sending a number of messages directly in a single transaction or course of is named batching. This may improve throughput and decrease the overhead associated to performing quite a few separate duties.

• Batching may be applied on the enqueue and dequeue ranges.
• Utilizing queue arrays, a number of messages may be processed in bulk to scale back community site visitors.
• It might probably keep transaction integrity which makes positive that, messages are efficiently enqueued or dequeued.

Queue Monitoring and Efficiency Tuning

To ensure efficient operation and peak efficiency, Oracle queues, particularly these with Oracle Superior Queuing (AQ) — should be monitored and performance-tuned in just a few vital methods. This is a complete technique:

• To verify the queue is staying inside affordable bounds, periodically test its depth and dimension.
• To question queue statistics, together with the variety of messages (NUM_MESSAGES), the scale of the queue as of proper now (CURRENT_SIZE), and the utmost dimension of the queue (MAX_SIZE), use the DBA_QUEUE_TABLES and DBA_QUEUES views.
• Monitor knowledge reminiscent of common message dimension (AVERAGE_MESSAGE_SIZE), processing occasions (ENQUEUE_TIME, DEQUEUE_TIME), and enqueue and dequeue charges (ENQUEUE_RATE, DEQUEUE_RATE).
• To decrease the overhead of particular person transactions, use batch processing (BULK ENQUEUE and BULK DEQUEUE).
• To gather these metrics, use Oracle Enterprise Supervisor or customized scripts that question the DBA_QUEUE_SCHEDULES and DBA_QUEUE_SUBSCRIBERS views.
• Regulate the transaction parameters (DEQUEUE_BATCH_SIZE, COMMIT_BATCH_SIZE) to strike a steadiness between commit frequency and transaction dimension.
• Monitor messages that fail to enqueue or dequeue attributable to points by retaining a watch on the error queues (DBA_QUEUE_ERRORS).
• Use Oracle efficiency instruments like AWR stories (DBMS_WORKLOAD_REPOSITORY) and ASH stories (DBMS_ACTIVE_SESSION_HISTORY) to investigate queue-related efficiency metrics.

Integration With Oracle Streams and Oracle Goldengate

Superior queues may be built-in with each Oracle Streams and Oracle Goldengate to supply dependable and environment friendly knowledge integration and replication processes inside Oracle databases. Streams is a built-in function of Oracle Database used for knowledge replication and messaging. Whereas, with real-time knowledge motion and synchronization throughout heterogeneous techniques, Oracle Goldengate is an entire knowledge integration and replication answer.

• Streams guarantee dependable message supply and consistency throughout distributed techniques.
• It permits real-time propagation of messages and knowledge modifications throughout the enterprise.
• It helps varied knowledge codecs and kinds, making it appropriate with completely different integration situations.
• Oracle AQ can act as a supply or goal for Oracle Goldengate, enabling bidirectional knowledge replication and synchronization.

Additionally, it helps integration throughout completely different platforms and databases past Oracle, enhancing enterprise knowledge integration capabilities and making extra appropriate choices for choosing Oracle superior queue.

Use Case and Eventualities

Up to now, we’ve seen the in-depth of Oracle Advance Queue, lastly ramping up the guild with a use case and affected state of affairs, whereas choosing Oracle AQ.

• Occasion-driven structure for real-time knowledge

Enqueuing messages are saved regionally on particular occasions. Payloads are dequeued to course of and have an effect on downstream purposes or processes.

• Asynchronous Processing for decoupled purposes

Devices (funding securities) are getting opened parallelly through knowledge refresh from exterior knowledge suppliers. The processing of 1 safety is completely unbiased of one other therefore in the actual enterprise world there’s nearly no stoppage.

• Batch and Scheduling in a managed method

Enqueuing job requests into an AQ queue, the place a devoted job processing software dequeues and executes jobs in keeping with outlined schedules or priorities.

• Scalability and Load Balancing to deal with parallel processing and elevated load

Oracle AQ is successfully dealing with bulk and processing a number of payloads at a time.  

Finest Practices and Troubleshooting

• It is strongly recommended to make use of computerized segment-space administration (ASSM) tablespaces for the AQ queue tables.
• The queue desk indexes, and index-organized tables (IOT)s are routinely merged by AQ background processes. Nevertheless, they need to proceed to be monitored and coalesced if wanted.
• Oracle Actual Software Clusters (RAC) can be utilized to supply excessive availability and scalability to AQ. The efficiency of AQ may be improved by permitting completely different queues to be managed by completely different RAC situations.
• Make sure that there are sufficient queue monitor processes operating to carry out the background duties. The queue monitor should even be operating for different essential background actions.
• Make sure that statistics are being gathered in order that the optimum question plans for retrieving messages are being chosen. By default, queue tables are locked out from the automated gathering of statistics.
• Dequeue with a wait time ought to solely be used with devoted server processes. In a shared server atmosphere, the shared server course of is devoted to the dequeue operation during the decision, together with the wait time. The presence of many such processes may cause extreme efficiency and scalability issues and can lead to impasse.
• Batching a number of dequeue operations on multi-consumer queues right into a single transaction, utilizing NEXT because the navigation mode if not utilizing message priorities, and utilizing the REMOVE_NODATA dequeue mode if dequeuing in BROWSE mode adopted by a REMOVE.

Conclusion

Oracle AQ offers a strong basis for creating scalable, reliable, and event-driven purposes in Oracle Database environments, making it very best for a variety of enterprise use circumstances that require environment friendly messaging and knowledge integration capabilities.

AQ options like various service high quality, computerized message transformations, and propagations allow enterprises to create a sturdy and adaptable messaging platform. Database-integrated Superior Queuing permits real-time stream of important data, reduces administration, and boosts productiveness to your scalable, extremely obtainable group.

If the enterprise already has an Oracle platform, it’s extremely beneficial to make use of superior queueing on the enterprise stage to cater to varied knowledge factors throughout completely different techniques.

If the enterprise is doing a feasibility evaluation to pick out the right platform and atmosphere, they’ll definitely think about, Oracle and Oracle Advance Queue, as it’ll give them a sturdy, scalable platform on which the group can construct an IT panorama.