Don't destory your certificate if you dabble with SQL 2008 Encryption
Martin is continuing to post some great new posts on his
blog. I thought the last one is a real nasty one.
http://sqlblogcasts.com/blogs/martinbell/archive/2009/06/29/After-disabling-tde-you-still-requires-certificates-to-restore-the-database.aspx
If you have enabled TDE on a database and encrypted some data then remove the
TDE and backup, you may not be able to restore that backup if you don't have the
certificate.
I am guessing that this is to do with the encryption when you turn TDE on
being a background task, I expect the same is true in reverse, i.e. pages stay
encrypted until a background process decrypts them.
I wonder if the database ever gets back to a totally unencrypted
version
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