I think it eventually does get deleted. > Compaction is an online operation which reclaims the space used by the deleted and duplicate needles (needles with th

I think it eventually does get deleted. > Compaction is an online operation which reclaims the space used by the deleted and duplicate needles (needles with the same key). It creates a new haystack by copying needles while skipping any duplicate or deleted entries. Once done it swaps the files and in-memory structures. Just in an efficient way for FB