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Re: How to alter a trigger atomicly?
Posted by: Sorin Stoiana
Date: April 06, 2007 03:03AM

The problem was altering the trigger atomicly.

I've tried the following:

1. Lock the table, drop trigger, create trigger with new content, release lock.
LOCK TABLES `test` WRITE;
DROP TRIGGER test_trig;

At this point, the thread just hangs. See bug report http://bugs.mysql.com/bug.php?id=23713 .

2. Calling a stored procedure from the trigger, and altering the stored procedure. This method has problems with locking the `test` table, because you can't hold a WRITE lock on mysql.proc along with locks on other tables.

3. GET_LOCK() function seems to have some problems too. I haven't quite put my finger on what the problem is, because of the complexity of the app I'm working on right now. However, implementing a locking scheme with GET_LOCK() might work for you.

4. Right now, I'm messing around with IPC semaphores in PHP ...


Can anyone suggest a sollution? My app has a constant stream writes on the `test` table, and I have to update the trigger on the fly, without missing any INSERT/UPDATE/DELETE on the table.

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