
What Is New About NewSQL? - ceohockey60
https://softwareengineeringdaily.com/2019/02/24/what-is-new-about-newsql/
======
nikato
I’m sorry but I stopped reading after:

> Correctness and consistency were the two important metrics, rather than
> today’s metrics of performance and availability.

Not sure if his author has ever worked on an actual real world commercial
system.

~~~
xkcd-sucks
> Correctness and consistency were the two important metrics, rather than
> today’s metrics of performance and availability.

Sounds exactly like what the businessy people say to me. I've just learned to
stop responding honestly.

~~~
nikato
Haha yeah. In my experience running top internet sites, honestly if you don’t
have consistency you probably have a very unskilled engineering team, or you
don’t need availability either because your company is irrelevant.

A good question for someone who doesn’t think consistency is important is: If
you have 200 different records that should all be the same but are different
due to lack of consistency, which one of those records do you believe? Usually
met by blank stares.

~~~
throwaway2016a
> Haha yeah. In my experience running top internet sites, honestly if you
> don’t have consistency you probably have a very unskilled engineering team,
> or you don’t need availability either because your company is irrelevant.

So Twitter and Facebook must have horrible teams. Both of those if you update
your profile it may take minutes (and certainly seconds) until everyone has a
copy.

When running a site at large scale consistency becomes a business concern. Is
it really important to my business that if someone loads a profile 10 seconds
after they changed their avatar it is still the old version? The answer is
probably "no" and if it is, you can scale a lot larger and on cheaper hardware
than if you answer "yes"

Hardly any NoSQL database offer consistency or if they do they have eventual
consistency as a default. Because for most applications it doesn't matter.

Take a blog as another example... if two people hit the homepage the moment
after a new article is published does it really matter if one of them still
gets the old article?

Edit: To try to be helpful...

> A good question for someone who doesn’t think consistency is important is:
> If you have 200 different records that should all be the same but are
> different due to lack of consistency, which one of those records do you
> believe? Usually met by blank stares.

This is not even remotely what lack of consistency means in the context of
distributed systems. In the context of distributed systems they are talking
about transactional consistency. I.e. if you hit two servers they each return
the same result at that exact moment in time. No one is arguing that the two
servers are permanently inconsistent such as in your example just that they
are momentarily inconsistent since in a distributed system the cost of
consistency is extremely high.

~~~
perl4ever
"in a distributed system the cost of consistency is extremely high"

I feel like this might be related to the reason why the universe was designed
with a top speed.

~~~
pintxo
Isn‘t the cost extremly high, because there is a top speed? If data could be
moved instantaneously from a to b, then consistency should be easier to
achieve

