Triggers

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Triggers

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sqlzealot-81

Posted Monday, February 28, 2011 5:12 AM

Right there with Babe

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Hi,

I would like to know the difference between disabling and dropping a trigger. To me, Trigger is basically coupled with transaction hence write/reads entry from the log for the action. If that is the case, disabling a trigger would only stop the read operation however the write happens to the transaction log. For a big table with more transactions(updates/delete/insert), it would be great if we can drop the trigger instead of disabling so I can save the log file growth. So dropping a trigger would be the best one rather than disabling if it is not going to use in future.

Please correct me perhaps I am wrong on anything.

Post #1070431

Rome1981

Posted Monday, February 28, 2011 5:47 AM

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If you aren't going to use the trigger anymore, drop it. If you do plan on using it in the future, I would disable it. Another alternative is to script the trigger out and recreate it/drop it with a script or job.

Post #1070442

HowardW

Posted Monday, February 28, 2011 5:59 AM

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Whether you have triggers on a table or not has no bearing on whether transactions are written to the transaction log. All transactional operations are logged (in all recovery models) so you will not gain anything tangible by dropping vs disabling a trigger.

Also, triggers do not operate asyncronously, somehow mining the transaction log. They will be fired for each relevant DML statement as part of the same transaction.

Post #1070449

sqlzealot-81

Posted Monday, February 28, 2011 5:59 AM

Right there with Babe

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Thanks for your comment!!!

Am really looking for an answer or confirmation as how the disabling of a trigger is working. As I mentioned, is this the way that it will log an entry in transaction log but it wont read from it or it wont write the entry at all if it is in disabled state?

Post #1070451

HowardW

Posted Monday, February 28, 2011 6:05 AM

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sqlchanakya (2/28/2011)

Am really looking for an answer or confirmation as how the disabling of a trigger is working. As I mentioned, is this the way that it will log an entry in transaction log but it wont read from it or it wont write the entry at all if it is in disabled state?

No, triggers have absolutely no effect on whether the original transaction gets logged to the transaction log.

Post #1070454

sqlzealot-81

Posted Monday, February 28, 2011 6:11 AM

Right there with Babe

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Could you plese check the below link and correct me where I interpreted wrongly...

http://sqlblogcasts.com/blogs/tonyrogerson/archive/2006/10/27/1248.aspx

Post #1070457

HowardW

Posted Monday, February 28, 2011 6:26 AM

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Interesting...

That is written for 2000 (this is the 2008 forum) - what it's saying is that because the inserted and deleted tables need to include all columns, not just the ones affected by the update, some operations may end up with increased logging information.

I've never heard of this before and I can't see any official reference that supports it, but it does make some sense. I suspect that the huge changes between 2000 and 2008 will have changed this one way or another, however I'll see if I can do some digging (if one of the heavy weights hasn't answered it definitively by then)

Post #1070464

sqlzealot-81

Posted Monday, February 28, 2011 6:31 AM

Right there with Babe

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Okei, In Paul Randal's blog, he mentioned for SQL 2005 or behind, they changed the way the trigger working. But I could not find how it works.

I would really appreciate if you could help me on the same as you said....I would also definitely look and share the same.

Post #1070466