I have done extensive research on CDC and it almost never works out because most utilities don't create compressed archives in an "rsyncable" (rsync does CDC) format, I actually saved a lot of storage using restic when I switched my backups of certain things so that files were stored in archives uncompressed, and sorted in a stable order. I know syncthing eventually removed CDC and just went with constant-size block sizes.

Bazel, on the other hand, is completely in control of this, and it makes perfect sense to do this at that point -- and it seems to be a relatively efficient implementation too, really nice to see!

This is something I'm very interested in implementing for Docker builds. I've tested out CDC for the final image outputs, it results in smaller outputs but requires tuning between saved space versus request count when pulling. For build cache it might be even more advantageous.

Doesn't this mean that malicious inputs can deliberately cause super tiny or super huge chunks?