

Linearizability versus Serializability - r4um
http://www.bailis.org/blog/linearizability-versus-serializability/

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sbahra
How does linearizability provide "real-time" guarantees? It does not unless
some uncommon version of "real-time" is being used here.

~~~
jude-
Let's assume for a second that the effects of general relativity are
negligible, and that as external observers of the system, we can see the
global ordering of operations on an object as issued by all participating
machines.

"Real-time" in this context means all participants observe operations on an
object in the order in which they were issued. Not only do all participants
see the same total ordering of operations, but that total ordering is the same
as the ordering that we would see as global external observers.

Contrast this to serializability, which only guarantees that all participants
observe the same total ordering of operations. The order does not need to be
consistent with the ordering we would see. For example, if we see that write
W1 was issued before write W2, serializability means that the participants
must either all agree that W1 occurred before W2, or all agree that W2
occurred before W1. Linearizability means that they _must_ agree that W1
happened before W2, since W1 temporally precedes W2.

~~~
sbahra
Sure, but this is not a "real-time guarantee".

~~~
jude-
"Real-time guarantee" in the context of consistency models (i.e. this article)
means something _completely different_ from "real-time guarantee" in the
context of operating systems.

