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copied!<p>It seems that the pertinent question here is:</p> <ul> <li>Why would a scripted rollback ever be preferable to a full database restore from a backup taken immediately before the upgrade?</li> </ul> <p>I can think of several reasons:</p> <ol> <li><p>The database is very large - say a few hundred GB - and your company cannot afford the downtime and/or administrative overhead that would be involved in a full restore.</p></li> <li><p>A bug was introduced that was not discovered until a week or two into production. If you've never experienced this before, you're lucky. Once you've got a week's worth of transactions in the new database, you can forget about just restoring from backup.</p></li> <li><p>The bug was not discovered until <em>months</em> into the release. In other words, you don't even <em>have</em> the backup anymore, and you're officially in damage control/disaster recovery mode. I've never experienced this, but I've heard stories. It's a scary thought - how do you undo all the damage that was done? In this case your downgrade might not be perfect, but it might still be better than the alternative.</p></li> <li><p>By contrast, perhaps the database changes were trivial - adding a few rows here, a few triggers there. In this case, a scripted rollback is going to take <em>much</em> less time than a restore. It's possible that some things that took hours to upgrade - such as creation of new indexes or addition of new columns - may only take seconds to downgrade (drop).</p></li> <li><p>You're deploying to customer sites. Some of them may not have backups at all (yeah, it's pathetic, but there's nothing you can do about it). If one of them needs a rollback, this is your only option.</p></li> </ol> <p>There may be other reasons to have downgrade scripts - this is just off the top of my head.</p>

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