java - 如何在 Oracle AQ 中停止在未经确认的情况下删除消息？

Question

我已经设置了单个客户 Oracle AQ。我在 Java Web 应用程序中使用 CLIENT_ACKNOWLEDGE 模式观察来自此队列的消息。但是，一旦我在 onMessage 方法中收到消息，这些消息似乎就会从 Oracle 队列中删除。我的假设是，除非我在客户端中确认，否则该消息不应被删除。我该如何阻止这个？

Oracle 队列架构如下所示:

BEGIN DBMS_AQADM.CREATE_QUEUE_TABLE(
  Queue_table => '"TESTUSER"."myqueuetable"', 
  Queue_payload_type => 'TESTUSER.messageobject', 
  multiple_consumers => false
);
END;
/

BEGIN DBMS_AQADM.CREATE_QUEUE(
  Queue_name => 'TESTUSER.myqueue', 
  Queue_table => 'TESTUSER.myqueuetable', 
  Queue_type => 0, Max_retries => 5, Retry_delay => 0
);
END;
/

BEGIN dbms_aqadm.start_queue (
  queue_name => 'testuser.myqueue'
);
END;

我像这样观察 Java 应用程序中的消息

 //somewhere in my app
session = queueConnection.createQueueSession(false, Session.CLIENT_ACKNOWLEDGE);
queueReceiver = ((AQjmsSession) databaseConnectionManager.getSession())
 .createReceiver(databaseConnectionManager.getQueue(), Messageobject.getORADataFactory());
queueReceiver.setMessageListener(this);


//in my listener class
@Override
public void onMessage(Message message) {
 AdtMessage msg = (AdtMessage) message;

 try {
  Messageobject message = (Messageobject) msg.getAdtPayload();

  if (isUserConnected(message.userId)) {
   logger.debug("Message acknowledged");
   msg.acknowledge();
   //handle the message. the message should be deleted now.
  } else {
   //i don't want the message to be deleted
  }

 } catch (JMSException | IllegalArgumentException | SQLException e) {
  logger.error("An error occurred while sending an outgoing blob", e);
 }
}

Answer 1

您正在创建一个消费者队列，该队列的消息在成功消费后立即被删除。

要保留消息，请在创建队列时将retention_time设置为大于零的值。

BEGIN 
  DBMS_AQADM.CREATE_QUEUE(
    Queue_name => 'TESTUSER.myqueue', 
    Queue_table => 'TESTUSER.myqueuetable', 
    Queue_type => 0, Max_retries => 5, Retry_delay => 0,
    retention_time => 300    -- retain for next 5 minutes
  );
END;
/

引用https://docs.oracle.com/database/121/ARPLS/d_aqadm.htm#ARPLS109