
Dividing Infinity – Distributed Partitioning Schemes - kiyanwang
http://eventql.io/blog/dividing-infinity-distributed-partitioning-schemes/
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contravariant
>Within the keyspace, identifiers are well-ordered [6]. That means each ID has
a successor and a predecessor.

Minor nitpick, but really it only guarantees a successor. In particular the
natural numbers are well ordered, but 0 (or 1, depending on what convention
you're using) doesn't have a predecessor.

Edit: worse the keyspace depicted doesn't appear to be well ordered since it
doesn't seem to have a lower limit. It's possible the author meant "totally
ordered" although strictly speaking that also doesn't guarantee a predecessor
or successor.

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rdtsc
> Minor nitpick, but really it only guarantees a successor.

That's from the consistent hashing chapter. That uses a ring usually
[0,2^p-1]. With p=160 if SHA is the hash algorithm. Then the predecessor of 0
is then 2^p-1.

~~~
contravariant
In that case it's still neither well ordered, or even 'ordered' in any
mathematical sense. I was merely pointing out that 'well ordered' doesn't
convey whatever it was the author was trying to say.

