> I am sure that the deletion of media files in services like Facebook has never meant to be absolute. Many of my colleagues believe the same thing that I believe: Facebook and other services do not actually delete data, they just mark it as "deleted" and purge it only if they need the space.
No reason to believe. You can read about the storage architecture used to store photos from a post in 2009 here: https://code.facebook.com/posts/685565858139515/needle-in-a-.... Obviously that might and probably has changed since, but at least at some point that was exactly true.
Quote:
"The delete operation is simple – it marks the needle in the haystack store as deleted by setting a “deleted” bit in the flags field of the needle. However, the associated index record is not modified in any way so an application could end up referencing a deleted needle. A read operation for such a needle will see the “deleted” flag and fail the operation with an appropriate error. The space of a deleted needle is not reclaimed in any way. The only way to reclaim space from deleted needles is to compact the haystack (see below)."
No reason to believe. You can read about the storage architecture used to store photos from a post in 2009 here: https://code.facebook.com/posts/685565858139515/needle-in-a-.... Obviously that might and probably has changed since, but at least at some point that was exactly true.
Quote:
"The delete operation is simple – it marks the needle in the haystack store as deleted by setting a “deleted” bit in the flags field of the needle. However, the associated index record is not modified in any way so an application could end up referencing a deleted needle. A read operation for such a needle will see the “deleted” flag and fail the operation with an appropriate error. The space of a deleted needle is not reclaimed in any way. The only way to reclaim space from deleted needles is to compact the haystack (see below)."