Control Z in a NoSQL world

I was going on a trip with my 13 year old son, and out of the blue, he said "What if you can hit 'Command Z' in the real world?"  "What?" "What if you spilled your drink and you hit 'Command Z' and it never happened?" Silence indicating my mind blowing. As a millennial raised in age of the Internet and cloud computing, he was wondering if our real world actions can be as transient as our virtual world. In the laws of physics, entropy says that energy and structure will break down, and processes tend not to be reversible. But have we defied the laws of physics in our virtual world? I remember how awesome it was to use a word processor and learn how to fix typos. In high school, typos were fixed with correction tape and there always a little smudge to indicate that mistake was made. Meanwhile, 'Control Z' just makes your actions go away as if it never happened. My son's comments made me think if I wanted to 'Control Z' any thing I have done in my life. The reality is that like everyone I have regretted actions and decisions I have made and the resulting consequences. But these same actions may have also had some wonderful consequencesor at least lessons. So I don't think I would have used 'Control Z'. I would live with smudges in my life. 

In our virtual world, 'Control Z' is not as powerful as it seems. Our Email is archived and backed up to other systems. Gmail recently came out with a limited message unsend feature, but this only works for a limited period after hitting the send button. Facebook posts can be shared and propagated pretty soon after you have posted and even if you retract a post, it lives on in some archive. 

What does this mean in a NoSQL world? NoSQL databases are powering the internet these days, and though it is not required these data stores often contain denormalized data where data facts are often stored in multiple places. For instance a user name may be stored in a user profile and also in all that user's posts, comments and likes. Let's say a user gets married and as a traditional person she changes her last name. Then all her posts, comments and likes need to be updated. SQL databases usually solve this problem by storing the name once and using an immutable primary key for the user that is stored in the posts, comments and likes. Then the two tables are joined to show the name. NoSQL usually does not join its objects and hence the need to denormalize or repeat the data. This makes 'Contol Z' much harder and reminds of us that we do live in a world where actions leave a mark and those marks are hard to erase, and we have to live with the smudges that life gives us.