Question

我已经创建了一个Event，但无法弄清楚如何在运行时记录，需要多长时间以及是否有任何错误。我该怎么做？

CREATE EVENT ON SCHEDULE EVERY 5 MINUTE
DO BEGIN
    ...do something...
END

Answer 1

我将以下内容用于事件效果报告。

请注意，它可以处理您想要抛出的任意数量的单独事件（例如，您单独编码的N个事件）。

您的活动中的步骤取决于您。我在下面的事件中有一个参考，这里有一个未显示的表格，以及我在这个业务定制的事件中做的事情。显示所有这些将使这个答案太长。如果您是活动程序员，您会发现使用它。

此外，在您编写一些没有它们的简单事件之前，我的事件中的WHILE循环可能不是最好的。如果您没有安全地摆脱WHILE，您的活动将永远运行。所以，如果有的话，请记住这一点。

架构存根

下面的表由其代码顶部附近的事件使用，以对其执行插入，其唯一目的是获取唯一的id，以便在日志表的插入中使用。使用日期时间列等扩展它。它显示了一个简单的usedBy列来捕获至少一些东西，比如事件名称。主要是，它希望从中返回一个指定的auto_increment（id）。

drop table if exists incarnations;
create table incarnations
(   -- NoteA
    -- a control table used to feed incarnation id's to events that want performance reporting.
    -- The long an short of it, insert a row here merely to acquire an auto_increment id
    id int auto_increment primary key,
    usedBy varchar(50) not null
    -- could use other columns perhaps, like how used or a datetime
    -- but mainly it feeds back an auto_increment
    -- the usedBy column is like a dummy column just to be fed a last_insert_id()
    -- but the insert has to insert something, so we use usedBy
);

通用日志记录表如下：

drop table if exists EvtsLog;
create table EvtsLog
(   id int auto_increment primary key,
    incarnationId int not null, -- See NoteA (above)
    evtName varchar(20) not null,   -- allows for use of this table by multiple events
    step int not null,  -- facilitates reporting on event level performance
    debugMsg varchar(1000) not null,
    dtWhenLogged datetime not null
    -- tweak this with whatever indexes your can bear to have
    -- run maintenance on this table to rid it of unwanted rows periodically
    -- as it impacts performance. So, dog the rows out to an archive table or whatever.
);

示例事件

-- Now the event kicks in on the server on its interval schedule and processes the batch.
-- But we need to modify that Event code because prior all it did was write a row to the log table
-- saying it was looking around. But it didn't actually do anything
drop event if exists `Every_2_Minutes_QuestionUpdateImport`; 
DELIMITER $$
CREATE EVENT `Every_2_Minutes_QuestionUpdateImport`
  ON SCHEDULE EVERY 2 MINUTE STARTS '2015-09-01 00:00:00'
  ON COMPLETION PRESERVE
DO BEGIN
    DECLARE bContinue bool default true;
    DECLARE counter int default 0;
    DECLARE logMsg varchar(1000);
    DECLARE incarnationId int default 0;
    DECLARE evtAlias varchar(20);

    -- right here you could save `now()` into a variable, let's call it STARTEVT

    set evtAlias:='ev2minQUI';  -- a shorter unique alias name, max 20 chars

    -- Below we must acquire our incarnation id from the control table used for all events
    -- that want to use it. It facilitates performance reporting with the use of the `steps` column and the datetime
    -- that are put in the EvtsLog table
    insert incarnations(usedBy) values (evtAlias); -- see NoteA
    select last_insert_id() into incarnationId; -- an auto_increment handed to us by the control table

    insert EvtsLog(incarnationId,evtName,step,debugMsg,dtWhenLogged)
    select incarnationId,evtAlias,1,'Event Fired, begin looking',now(); -- 1: we are beginning

    WHILE bContinue DO  -- this is an intermediate-level skills event example. Be careful or you are stuck in the event forever
        select min(batchId) into @idToPerform 
        from EvtsQuestionsToImportBatchHandler -- table not shown in this post on Stackoverflow
        where batchStatus=1;    -- @idToPerform, a variable, will be null if there is no such row

        insert EvtsLog(incarnationId,evtName,step,debugMsg,dtWhenLogged)
        select incarnationId,evtAlias,5,'Debug Place 1',now(); 

        IF (@idToPerform IS NOT NULL) THEN

            -- This next update line is very crucial, to mark the batch as underway and never picked up again
            -- at the top of this WHILE loop (otherwise you may be stuck in here forever)
            update EvtsQuestionsToImportBatchHandler set batchStatus=2,dtProcessBegan=now() where batchId=@idToPerform;

            set counter:=counter+1; -- used outside of the while loop in the end

            insert EvtsLog(incarnationId,evtName,step,debugMsg,dtWhenLogged)
            select incarnationId,evtAlias,10,"a message maybe from concat and variables",now();
            --
            -- Here is where you actually do something
            -- Here is where you actually do something
            -- Here is where you actually do something

            insert EvtsLog(incarnationId,evtName,step,debugMsg,dtWhenLogged)
            select incarnationId,evtAlias,20,"a message maybe from concat and variables",now();  

            -- Here is where you actually do something
            -- Here is where you actually do something
            -- Here is where you actually do something

            insert EvtsLog(incarnationId,evtName,step,debugMsg,dtWhenLogged)
            select incarnationId,evtAlias,30,"a message maybe from concat and variables",now();  

            -- mark this batch as done:
            update EvtsQuestionsToImportBatchHandler set batchStatus=3,dtProcessFinished=now() where batchId=@idToPerform;
        ELSE
            set bContinue=false;    -- we are done with the event loop
        END IF;
        -- if bContinue is true, we will seek the next batch to process that has batchStatus=1, if there is one

        -- right here a new now() could be performed, and a timediff() against the STARTEVT
        -- to determine if you want to bail out also with a " set bContinue=false; "

    END WHILE; -- this is an intermediate-level skills event example. Be careful or you are stuck in the event forever

    -- this msg is crucial to see in the log table to know you are not locking in an endless WHILE loop
    set logMsg:=concat("Number of batches processed=",counter); -- concat example (could have been used above)
    insert EvtsLog(incarnationId,evtName,step,debugMsg,dtWhenLogged)
    select incarnationId,evtAlias,90,logMsg,now(); -- 90: we are almost done

    insert EvtsLog(incarnationId,evtName,step,debugMsg,dtWhenLogged)
    select incarnationId,evtAlias,99,'Event Done',now(); -- 99: we are done
END$$
DELIMITER ; -- sets the delimiter back to what we are used to, the semi-colon

当然，您会针对包含incarnationId，evtName，step和日期时间的日志表获得效果报告。以下查询将多行事件信息折叠为每个事件运行1行，并带有时间差。

select incarnationId,dtBegin,dtEnd,TIMESTAMPDIFF(SECOND,dtBegin,dtEnd) as secDiff
from
(   select incarnationId,min(dtBegin) as dtBegin,max(dtEnd) as dtEnd
    from
    (   select incarnationId,
        case  
            when step=1 then dtWhenLogged
        end as dtBegin,
        case  
            when step=99 then dtWhenLogged
        end as dtEnd
        from evtsLog
        where evtName='evtName01'
    ) d1
    group by incarnationId
) d2;
+---------------+---------------------+---------------------+---------+
| incarnationId | dtBegin             | dtEnd               | secDiff |
+---------------+---------------------+---------------------+---------+
|           101 | 2016-05-01 14:02:00 | 2016-05-01 14:02:01 |       1 |
|           102 | 2016-05-01 14:02:01 | 2016-05-01 14:02:07 |       6 |
+---------------+---------------------+---------------------+---------+

要以微秒为单位进行更精确的报告，需要MySQL 5.6.4或更高版本。请参阅此answer。

由于没有与之关联的UX，因此写入事件非常棘手。通过使用日志记录表，您不仅可以实现性能报告，还可以在开发过程中获得调试消息的洞察力。

不要忘记删除日志表以控制其大小。也许可以将它存档到某个地方（可能通过另一个事件！）。

Answer 2

\p{M}

会帮助你

我怎样才能有MySQL日志安排的事件？

2 个答案:

架构存根

示例事件