Yes, there will be impact. Shrink is an IO-intensive operation (does a huge amount of IO operations)

You're having stack dumps, severe exceptions which result in SQL writing out diagnostic information. Rather than worry about the space, maybe worry about why you're having a lot of very...

Sure. Shrink's an IO intensive operation.

No. Very bad idea, not the correct way to manage a log at all.

Please take a read through this: http://www.sqlservercentral.com/articles/Administration/64582/

Edit: There's also a stairway series on log management that goes...

First things first, take that agent job out. Scheduling some major performance degradation is usually not something you do to a production system.

Is it SQL which is consuming the memory?...

Sure. Shrink is a fully online operation. Not something that should be run often, only under exceptional situations though.

A nonclustered index that is defined as unique (CREATE UNIQUE NONCLUSTERED INDEX ...) enforces uniqueness on its key columns. A nonclustered index defined without the unique keyword doesn't.

Not that...

I suspect I know why, but don't have time to write an essay tonight (and that's what is required to explain it)

The EXISTS adds a row goal of 1 into...

This.

t.b.h. if a candidate mentioned...

mike.gallamore (3/18/2014)

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Also truncate vs delete: if you think you might ever want to roll back this operation use delete, it will be sent to the transaction log so you can...

Yes

Check the value...

I think you maybe need to go back to the drawing board, get the requirements clear and then sit down with someone there who knows SQL and go through how...

Um...

What kind of 'impact'?

You are going to recreate the unique constraint immediately?