This is not scary movie but Facebook users are equally annoyed because their deleted messages are reappearing after a recent Message Center update. Facebook has been known for retaining data and it was made clear in many earlier instances that deleting a data from anywhere on the Internet does not necessarily mean it is deleted.
A few months ago, there was this news on deleted Facebook photos being available even after deletion. They were available at the same old links. It was explained with theories like the data remains in the CDN that stores media content for services like these. However, this is only part of the story.
The real story of why things never get deleted on Facebook
Any deletion you perform happens only on the frontend. In simpler words, if you delete a photo on Facebook, Facebook makes changes to your account in such a way that it never comes back to you as an object accessible from the user-interface, but it is still out there. The same goes for messages and other things. I was taught the same thing during my first web-design classes and it felt really creepy. Though, this does happen at a lot of places. It saves the database from getting overheads from deletion and it is easier to run a small update query (for something like a deleted bit or flag) instead of a large resource intensive delete query on a database.
In the problem the user faced above, the Message Center update team (that’s what I am calling them) at Facebook did not go through the documentation well enough to take note that there was some code to make sure the user does not see his deleted messages. The developers of the Message Center completely overlooked that feature and will have to push updates to correct this bug.
Now, Facebook can boast all about how it uses Bittorrent technologies to push updates across its distributed servers but glitches and bugs like these make it look outright stupid. Whatever happened to testing codes before releasing them half baked? Facebook is not a one man show that it can be excused for this glitch. A full blown company competing with online tech giants, a company that upsets privacy watchdogs every day and a company which is the largest social network in the world cannot afford to make mistakes like these.
Note: It would be a lie to say things never get deleted on Facebook. But they stay for a seemingly indefinite amount of time.