VS2010 Database Project Deployment, to fail if data loss may occur or not?

I have a database project for a web app, and currently I have it configured to fail if data loss may occur during deployment. I feel safer this way. However I've run into a problem. I actually need to deploy changes on some things where I'm okay with the possible data loss, i.e. shortening column lengths where nothing would actually get deleted, but the system thinks it would.

I have 2 questions.

The first is this: other than enabling or disabling the catch all go or no go, is there any way to have more granular control over this process, i.e开发者_如何转开发. specify columns it's okay to drop or shorten? Is there any way to get more granular control of this process?

The second is, how do you guys handle these situations? Initially I had hoped that adding a pre-deployment script to drop the columns would be sufficient, however it seems to catch drops etc. in those files as well.

1. No there isn't any way to control it at a more granular way unfortunately.
2. I disable it when I know I'll be deploying something that will cause data loss but is what I want. Then I re-enable it after. Also, I would always check the change script that comes out when deploying to production.

Just update the column in a pre-deployment script to the truncate length?

Eg : to truncate my col to 20 :

UPDATE mycol = LEFT(mycol, 20)
FROM mytable
WHERE mycol != LEFT(mycol, 20)

The Microsoft guidance is to move the data out into a temporary table in pre-deployment, let the deployment engine run a check to see whether the table contains rows (this will pass because it is now empty) and upgrade the schema, and move the data back in a post deployment script.

For more information, see Barclay Hills posts on the subject:

• Managing data motion during your deployments (Part 1)
• Managing data motion during your deployments (Part 2)