介绍

使用Oracle Advanced Queuing方法时,我在Oracle SQL Server上遇到了一个非常奇怪的行为(确切地说：Oracle Database 11g企业版11.2.0.4.0版 – 64位生产版).

问题

错误是我将X消息排队,但是dequeue_array返回X 1消息,第一条消息重复(如MessageId所示).

复制：

我能够编写一些简单的PoC来重现错误.本代码非常简单,入队/出队的东西是标准的Oracle AQ.代码执行以下步骤两次(测试运行)：

>清除队列表

>排队X消息

>使用dbms_aq.dequeue_array调用使所有消息出列

>检查已出列的消息数

在新连接上运行POC时,第一次运行成功而没有错误,但每次后续运行都失败.之后,当使用相同的连接时,每次执行脚本时,它都会在两次测试运行中失败.

到目前为止我尝试了什么：

>在“新”连接上运行此脚本：仅第一次运行失败

>在同一连接上执行脚本的任何其他操作：所有运行都失败

>使用/创建新队列时：只有第一次运行失败

>使用“从< queue_table>中删除”时而不是dbms_aqadm.purge_queue_table()：一切都很好

>当使用“正常”一个一个出列时：每次都很好

结论：

我既不能解释这种行为,也不能在我的代码中找到错误.请看一下它,它应该可以在你最喜欢的sql客户端中直接执行(用PL / SQL Developer测试).

如果您需要任何进一步的信息或在让PoC工作时遇到问题,请问,我会定期检查这个帖子.我试图使PoC尽可能可读,包括关于正在发生的事情的详细输出.

码：

declare

C_QueueName constant varchar2(32767) := 'TEST_QUEUE';

C_QueueTable constant varchar2(32767) := 'TEST_Q_TABLE';

C_MsgCount constant pls_integer := 1;

C_TestRuns constant pls_integer := 2;

C_DequeueArraySize constant pls_integer := 10;

/*

* Create the queue and the queue table used for theses tests

*/

procedure CreateQueueIfMissing is

L_Present pls_integer;

begin

dbms_output.put_line('START CreateQueueIfMissing');

execute immediate 'select count(*) from USER_OBJECTS where OBJECT_NAME = ''' || C_QueueName || ''' and OBJECT_TYPE = ''QUEUE''' into L_Present;

if L_Present = 1 then

dbms_output.put_line('Skipping queue creation, already present.');

dbms_output.put_line('END CreateQueueIfMissing');

return;

end if;

dbms_output.put_line(' Creating queue table ' || C_QueueTable);

DBMS_AQADM.CREATE_QUEUE_TABLE(queue_table => C_QueueTable

,storage_clause => 'LOGGING NOCACHE NOPARALLEL MONITORING'

,sort_list => 'priority,enq_time'

,multiple_consumers => false

,queue_payload_type => 'SYS.AQ$_JMS_BYTES_MESSAGE'

,comment => 'Queue for messages');

dbms_output.put_line(' Creating queue ' || C_QueueName);

DBMS_AQADM.CREATE_QUEUE(queue_name => C_QueueName

,queue_table => C_QueueTable

,max_retries => 8640

,retry_delay => 30

,comment => 'Queue for messages');

dbms_output.put_line(' Starting queue ' || C_QueueName);

DBMS_AQADM.START_QUEUE(queue_name => C_QueueName);

dbms_output.put_line('END CreateQueueIfMissing');

end CreateQueueIfMissing;

-- ================================================================================================

/*

* This procedure is the root of all evil.

* The error only occurs when using the purge_queue_tables procedure.

* When using a normal "delete from " then everything is just fine.

*/

procedure CleanQueueTable is

L_PurgeOptions dbms_aqadm.aq$_purge_options_t;

L_Count pls_integer;

begin

dbms_output.put_line('START CleanQueueTable');

execute immediate 'select count(*) from ' || C_QueueTable into L_Count;

dbms_output.put_line(' Messages in queue table BEFORE purge: ' || L_Count);

dbms_aqadm.purge_queue_table(queue_table => C_QueueTable

,purge_condition => null

,purge_options => L_PurgeOptions);

execute immediate 'select count(*) from ' || C_QueueTable into L_Count;

dbms_output.put_line(' Messages in queue table AFTER purge: ' || L_Count);

dbms_output.put_line('END CleanQueueTable');

end CleanQueueTable;

-- ================================================================================================

/*

* Enqueue the configured count of messages on the queue

*/

procedure EnqueueMessages is

L_BodyId pls_integer;

L_Msg sys.aq$_jms_bytes_message;

L_MsgId raw(16);

L_Count pls_integer;

L_EnqueueOptions DBMS_AQ.ENQUEUE_OPTIONS_T;

L_MessageProperties DBMS_AQ.MESSAGE_PROPERTIES_T;

begin

dbms_output.put_line('START EnqueueMessages');

execute immediate 'select count(*) from ' || C_QueueTable into L_Count;

dbms_output.put_line(' Messages in queue table BEFORE enqueue: ' || L_Count);

for i in 1 .. C_MsgCount

loop

dbms_output.put_line(' Construct #' || i);

L_Msg := sys.aq$_jms_bytes_message.construct;

-- set the JMS header

L_Msg.set_type('JmsBytesMessage');

L_Msg.set_userid(1);

L_Msg.set_appid('test');

L_Msg.set_groupid('cs');

L_Msg.set_groupseq(1);

-- set JMS message content

L_BodyId := L_Msg.clear_body(-1);

L_Msg.write_bytes(L_BodyId, to_blob(utl_raw.cast_to_raw('Lorem Ipsum')));

L_Msg.flush(L_BodyId);

L_Msg.clean(L_BodyId);

dbms_output.put_line(' Enqueue #' || i);

DBMS_AQ.ENQUEUE (queue_name => C_QueueName

,enqueue_options => L_EnqueueOptions

,message_properties => L_MessageProperties

,payload => L_Msg

,msgid => L_MsgId);

end loop;

execute immediate 'select count(*) from ' || C_QueueTable into L_Count;

dbms_output.put_line(' Messages in queue table AFTER enqueue: ' || L_Count);

dbms_output.put_line('END EnqueueMessages');

end EnqueueMessages;

-- ================================================================================================

/*

* Dequeues messages using dequeue_array from the configured queue.

*/

procedure DequeueMessages is

L_DequeueOptions dbms_aq.dequeue_options_t;

L_MsgPropArr dbms_aq.message_properties_array_t := dbms_aq.message_properties_array_t();

L_PayloadArr sys.aq$_jms_bytes_messages;

L_MsgIdArr dbms_aq.msgid_array_t;

L_MsgCnt pls_integer := 0;

L_Count pls_integer;

begin

dbms_output.put_line('START DequeueMessages');

execute immediate 'select count(*) from ' || C_QueueTable into L_Count;

dbms_output.put_line(' Messages in queue table BEFORE dequeue: ' || L_Count);

L_MsgCnt := dbms_aq.dequeue_array(queue_name => C_QueueName

,dequeue_options => L_DequeueOptions

,array_size => C_DequeueArraySize

,message_properties_array => L_MsgPropArr

,payload_array => L_PayloadArr

,msgid_array => L_MsgIdArr);

execute immediate 'select count(*) from ' || C_QueueTable into L_Count;

dbms_output.put_line(' Messages in queue table AFTER dequeue: ' || L_Count);

dbms_output.put_line(' Expected: ' || C_MsgCount || ', Received: ' || L_MsgCnt);

if C_MsgCount != L_MsgCnt then

dbms_output.put_line(' *****************************************');

dbms_output.put_line(' TOO MANY ITEMS DEQUEUED?!?');

dbms_output.put_line(' *****************************************');

for i in 1 .. L_MsgCnt

loop

dbms_output.put_line(' #' || i || ' MsdId=' || L_MsgIdArr(i));

end loop;

end if;

dbms_output.put_line('END DequeueMessages');

end DequeueMessages;

-- ================================================================================================

/*

* This is the testcase

*/

procedure RunTestCase is

begin

CreateQueueIfMissing;

for i in 1 .. C_TestRuns

loop

dbms_output.put_line(null);

dbms_output.put_line('=========== START test run #' || i || '===========');

CleanQueueTable;

EnqueueMessages;

DequeueMessages;

end loop;

end;

-- ================================================================================================

begin

RunTestCase;

end;

示例输出：

START CreateQueueIfMissing

Skipping queue creation, already present.

END CreateQueueIfMissing

=========== START test run #1===========

START CleanQueueTable

Messages in queue table BEFORE purge: 0

Messages in queue table AFTER purge: 0

END CleanQueueTable

START EnqueueMessages

Messages in queue table BEFORE enqueue: 0

Construct #1

Enqueue #1

Messages in queue table AFTER enqueue: 1

END EnqueueMessages

START DequeueMessages

Messages in queue table BEFORE dequeue: 1

Messages in queue table AFTER dequeue: 0

Expected: 1, Received: 1

END DequeueMessages

=========== START test run #2===========

START CleanQueueTable

Messages in queue table BEFORE purge: 0

Messages in queue table AFTER purge: 0

END CleanQueueTable

START EnqueueMessages

Messages in queue table BEFORE enqueue: 0

Construct #1

Enqueue #1

Messages in queue table AFTER enqueue: 1

END EnqueueMessages

START DequeueMessages

Messages in queue table BEFORE dequeue: 1

Messages in queue table AFTER dequeue: 0

Expected: 1, Received: 2

*****************************************

TOO MANY ITEMS DEQUEUED?!?

*****************************************

#1 MsdId=2949A0FF2EE456A7E0540010E0467A30

#2 MsdId=2949A0FF2EE456A7E0540010E0467A30

END DequeueMessages