Why did the .bak size drop after a full database backup?
So, I noticed this recently when I was doing a full database backup on one of our test servers. As the backup is executing, the filesize on disk shows 21,346,988 KB . Once the backup completed, the filesize on disk became 13,900,567 KB. I have not seen such a thing happen to other databases. The usual I see is a minor variation where the filesize grows a little more than initial. But not drop back like 7GB as what is happening is here. Why would such a thing happen?