I am trying to write an automated test script for testing a MySQL Event that I created, and I am wondering if there is a way to execute some kind of command to force the Event to execute immediately. The Event is set to run daily at midnight, but I don't want the automated test script to have to wait for the Event to trigger.
One way I can think of is to ALTER the Event to have it execute one-time 5 seconds into the future, but I'd like to know if there is a more elegant way to do get it to execute.
Move all the code within the event into a stored procedure
Make the event only call the stored procedure
Test the stored procedure with the CALL syntax.
if it is based on the system time, change that, and see if your event fires, then change the system time back.
Another 'proxy' solution is schedule it ver soon, for example:
ON SCHEDULE EVERY 10 SECOND
(or 1 sec, depends how long in the run time of the event).
you could later drop the event.
Related
I've built several stored procedures in MySQL. I would like to run them in a specific order to ensure that tables are updated properly and efficiently. What would be the best way to call the procedures to run in a specific order? I would like to have them run once every 30 minutes or so.
Thanks
After some research, I found that a recurring event for each procedure is a good way to go. Creating each event about 10 seconds apart ensures they run in sequence every 30 minutes.
CREATE EVENT `[Event_Name]`
ON SCHEDULE EVERY 30 MINUTE
DO
CALL `[Stored_Procedure_Name]`();
I am using a host gator shared hosting plan, and need to execute a simple command every minute:
UPDATE table_info SET expired = 1 WHERE TIMESTAMP(dateTime) <= NOW()
My problem is that I cant turn on the event scheduler because I don't have permissions for it. Can anyone think of a simple way to do this without using events?
You can put your update statement into simple PHP script, and run it via cron.
Using cron or any other OS based task scheduler is stricktly speaking an answer to this question.
However, it is not really a best practice to run any event every minute. Particularly not, if the operation done could be executed on the fly, like here. The expired flag's value depends on a simple calculation:
dateTime <= NOW()
Instead of running this calculation every minute on the entire table_info, you could
place the sql command into a regularly executed script
just embedd the logic into any reporting or other operation which depend on the expired field and get rid of the flag completely.
I am trying to use mysql event schedule in my application, I have not use it before so i have some confusions.
I want to know if my computer is off on the schedule date, then schedule will continue on next day, after starting my computer?
Like:
my schduled is for beginning at every month (no predefined time set)
if in the above date my computer/Server is off,
will mysql continue scheduled event in next day after turning on my computer/server?
If no, then please suggest a solution.
Hmmmm, have you looked at something like this?
MySQL: Using the Event Scheduler
... or:
How to create MySQL Events
... or even: [MySQL :: MySQL 5.1 Reference Manual: 19.4.1. Event Scheduler Overview](19.4.1. Event Scheduler Overview)?
Also please keep in mind that SQL DBMS servers are written with the rather strong presumption that they will be kept up and operating 24 hours per day with only brief periods of downtime for maintenance or repairs. There is generally very little consideration for operation on machines which are shutdown at night and while not in use.
If you simply store a table of dates and events then your can simply query that table for events which have passed or are upcoming within any range you like ... and you can run the program(s) containing those queries (and performing any appropriate activities based on the results) whenever you start you computer and periodically while it's up and running.
These links refer to a feature of MySQL which is designed to have the server internally execute certain commands (MySQL internal commands, such as re-indexing, creating/updating views, cleaning tables of data which "expires" and so on. I don't know if a MySQL server would attempt to execute all events which have passed during downtime, though it should only be a little bit of work to follow the tutorial, schedule some event for some time (say 15 minutes after the time you expect to hit [Enter]) ... then shutdown your computer (or even just the MySQL server) and go off to lunch. Then come back, start it up and see what happens.
The scheduled event could be something absurdly simple, like inserting the "current" time into some table you set up.
I have a stored procedure I'd like to run forever, but sleep for one second in a loop. When it wakes up it would poll a table to see if it should do some work. Work only needs to be done every minute, so there is no worry about the poll table getting hit with updates from two writers at the same time.
What is the best way to SLEEP() for an interval in a stored procedure? It would be nice, actually, if it could sleep for 200 milliseconds, but one second would work too.
I've encountered the same problem. After googling a lot, I found out that we can use
SELECT SLEEP(<seconds>);
to delay our procedures for this many seconds. In your case, using
SELECT SLEEP(0.2);
would be just fine.
You can use:
DO SLEEP(0.2);
Reference: http://dev.mysql.com/doc/refman/5.7/en/do.html
or
SELECT SLEEP(0.2);
Reference: http://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_sleep
MySQL has an event scheduler baked in. https://dev.mysql.com/doc/refman/5.6/en/events-overview.html
Sample:
CREATE EVENT performance_schema_snapshots.fill_events_statements_summary_by_digest_history1
ON SCHEDULE -- every day at 6 am
EVERY 1 DAY
STARTS TIMESTAMP(CURRENT_DATE) + INTERVAL 1 DAY + INTERVAL 14 HOUR
DO
-- take snapshot
CALL performance_schema_snapshots.events_statements_summary_by_digest_snapshot_reset ();
You dont specify which database you are using, but generally the way to achive what you want is not to have an infinetly running sproc but to have some external component - like a scheduler, or SQL Server Agent in MSSQL - execute the sproc every so often.
I have a PHP web application and when inserted in a table, I have written a trigger to calculate some scores and this takes time. My PHP application waits till the trigger completes.
Can this trigger run in a separate thread such that my application will not wait for the completion of the trigger?
No.
But as Bill Clinton would have said, "and I'll tell you why."
One of the big advantages of a trigger is that the actions of the trigger are contained within the transaction of the original statement that fired the trigger. This is a Good Thing from the Relational mindset because we like ACID compliance.
Now if you do not need that ACID compliance, and it is ok for the triggered actions to take effect "eventually", then remove the trigger and make an 'actions' table. Then either the trigger can drop something into the actions table or your PHP code might do it. You can have a job querying this table once/second or so, and if it finds anything it executes it. Don't worry about performance on the daemon, a once/second query of a table that is usually empty is nothing.