Question: Secure deletion of values

[ameba23]

I would like to be able to securely delete (zeroize) a value in a sled database.

Can i assume that if i overwrite a value by inserting a vector of zero bytes of the same length as the original stored value, the original value will no longer exist on disk?

Without knowing how sled represents values internally i cannot be sure if this is the case.

[reivilibre]

Not the author or an expert, but as sled is a log-structured database I would expect that when you delete a value, it will still exist on disk for the time being, but a tombstone entry will be persisted to mark it as deleted.
It's only once a compaction or garbage collection process happens later on, that the dead value might be removed.

[ameba23]

Not the author or an expert, but as sled is a log-structured database I would expect that when you delete a value, it will still exist on disk for the time being, but a tombstone entry will be persisted to mark it as deleted. It's only once a compaction or garbage collection process happens later on, that the dead value might be removed.

@reivilibre thank you for this. I tried both removing and overwriting values with zeros, and in both cases i was still able to read the original value directly out of the database file, so you are right.

I'm not sure if theres some way to manually trigger some cleanup process, i can't find anything about it in the docs.