Copy-on-write B-tree finally beaten.
I did not read the paper yet, but COW btrees are interesting for practical reasons since it is possible to update the tree just writing in append-only mode, that is nearly the only way to avoid fsync (or alike) but still avoiding trivial corruptions (the new root node is always written at the end of the update). Otherwise you either use fsync as a write barrier or live with the problem that from the OS to the disk itself writes reordering can corrupt very easily your data structure in the event of a crash.However I think that the real problem here is not at the algorithmic level, but at OS API level: just a provocation, don't you think that in the era of SSD drives where seeks are cheap is strange we resort to append only data structures?