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Bagaimana saya bisa membuat MySQL mencatat Acara yang dijadwalkan?

Saya menggunakan yang berikut ini untuk Pelaporan Kinerja Acara.

Perhatikan bahwa ia dapat menangani sebanyak mungkin peristiwa terpisah (misalnya N peristiwa yang Anda kodekan secara terpisah) yang ingin Anda berikan.

Apa yang Anda lakukan sebagai Langkah di dalam Acara Anda terserah Anda. Saya memiliki referensi di Acara di bawah ini ke tabel yang tidak ditampilkan di sini serta apa yang saya lakukan di Acara yang khusus untuk bisnis yang satu ini. Menampilkan semua itu akan membuat jawaban ini terlalu panjang. Jika Anda seorang programmer Acara, Anda akan menemukan Anda gunakan untuk itu.

Juga, WHILE loop di acara saya mungkin bukan yang terbaik sampai Anda membuat kode beberapa acara sederhana tanpanya. Jika Anda tidak menyelamatkan WHILE dengan aman, acara Anda akan berjalan selamanya. Jadi, ingatlah itu jika ada sesuatu di sini.

Stub skema

Tabel berikut digunakan oleh Peristiwa di dekat bagian atas kodenya untuk melakukan penyisipan terhadapnya, dengan tujuan semata-mata untuk mendapatkan id yang unik kembali untuk digunakan dalam sisipan ke tabel log. Perluas dengan kolom datetime atau sejenisnya. Ini menunjukkan usedBy trivial yang sepele kolom untuk menangkap sesuatu setidaknya, seperti nama Acara. Terutama, ia menginginkan kenaikan_otomatis yang ditetapkan kembali darinya (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
);

Tabel logging umum di bawah ini:

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.
);

Contoh Acara

-- 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 [email protected];

            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 [email protected];
        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

Secara alami, Anda mendapatkan Pelaporan Kinerja terhadap tabel log yang menyertakan incarnationId , evtName , step , dan waktu tanggal. Kueri di bawah ini menciutkan informasi acara multi-baris menjadi 1 baris per acara berjalan, dengan perbedaan waktu.

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 |
+---------------+---------------------+---------------------+---------+

Untuk pelaporan yang lebih tepat dalam mikrodetik, diperlukan MySQL 5.6.4 atau lebih tinggi. Lihat jawaban ini .

Acara sulit untuk ditulis karena tidak ada UX yang terkait dengannya. Dengan menggunakan tabel logging, Anda tidak hanya dapat mencapai pelaporan kinerja, tetapi juga memperoleh wawasan dengan pesan debug selama pengembangannya.

Jangan lupa untuk memangkas tabel log agar ukurannya tetap terkendali. Mungkin mengarsipkannya di suatu tempat (mungkin melalui Acara lain!).



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