Module 8 operation

Homework : Design message queue to store message data  MySQL  form

【 Job requirements 】

1.  Include table name 、 Field 、 Indexes ;2.  Use words to describe the design ideas and reasons , for example : Why design an index ?3.  One page  PPT  that will do .

【 Tips 】

1.  You need to consider one table per message queue , Or put all the messages in one table , Add a “ Queue name ” Field of .

answer ：

• Different task queues create different tables , such as xx_q, yy_q etc. . This reduces the size of each message table , Improve performance ; Reduce interference between different messages , Improve SQL Execution speed .

• Table structure

Here we use xx_q give an example , The main fields are as follows ：

CREATE TABLE `xx_q` (

  `id` bigint(20) NOT NULL AUTO_INCREMENT,

 //  Since the primary key

  `status` tinyint(4) DEFAULT 0,

 //  Queue type ：0: todo, 1: done

  `ps` int(11) DEFAULT 0,

 // Get the process number of the message , Equivalent to a lock  

  `ut` timestamp,

 // Time stamp

  `msg` json,

 // Message body parameters ,json Format preservation

  PRIMARY KEY (`id`),

  KEY `ut` (`ps`,`status`)

 // Traverse the index of the queue ,  Faster retrieval of messages

) 

• working principle ：

• Lock this work message ： update xx_q set ps=connection_id() , status=1 where ps = 0 and status=0 limit 1;

• Get message body ： select id, msg from xx_q where ps = connection_id() and status=1;

• Conduct   News consumption

• Delete the consumed message  delete from xx_q where ps = connection_id() and status=1;

• Clean up the messages occupied by the zombie process ： Time clearing   conversation id  No longer exists （ Abnormal exit ） but status=1  And   Zombie time exceeded 30 Minutes of news

update xx_q set status=0, ps=0 where status=1 and ps not in (`connection_id of 'show processlist'`) and ut < current_timestamp - interval 30 minute;