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Introducing Cloud Spanner, a Global Database Service

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Re: Introducing Cloud Spanner, a Global Database Service

#53
> Today, we’re excited to announce the public beta for Cloud Spanner, a globally distributed relational database service that lets customers have their cake and eat it too: ACID transactions and SQL semantics, without giving up horizontal scaling and high availability.

This sounds too good to be true. But it's Google, so maybe not. Time to start reading whitepapers...

Re: Introducing Cloud Spanner, a Global Database Service

#54

> Unlike most wide-area networks, and especially the public internet, Google controls the entire network and thus can ensure redundancy of hardware and paths, and can also control upgrades and operations in general I know this is a single system, but I'll still say it. This seems like another step in a scary trend for our internet.

This is no different from a myriad of other companies that have private networks on private fiber that span large geographical paths. Google's is probably bigger than most (both in terms of geography and throughput), but it's nothing new to have private fiber to ensure latency/throughput/reliability.

Re: Introducing Cloud Spanner, a Global Database Service

#55

I wonder how this will affect adoption of CockroachDB [1], which was inspired by Spanner and supposedly an open source equivalent. I'd imagine that Spanner is a rather compelling choice, since they don't have to host it themselves. As far as I know, CockroachDB currently does not support providing CockroachDB as a service (but it is on their roadmap) [2]. [1] https://www.cockroachlabs.com/docs/frequently-asked-questi…

I imagine the globally distributed database market is big enough for more than one winner. The presence of competitors can sometimes even be a boon, increasing the visibility of a market's goods relative to other similar goods.

Re: Introducing Cloud Spanner, a Global Database Service

#56
post #5

> Today, we’re excited to announce the public beta for Cloud Spanner, a globally distributed relational database service that lets customers have their cake and eat it too: ACID transactions and SQL semantics, without giving up horizontal scaling and high availability. This is a bold claim. What do they know about the CAP theorem that I don't? Separately, (emphasis mine): > If you have a MySQL or PostgreSQL system th…

Theoretically it means they are giving up on being Partition Tolerant. There was a popular post a while ago about how the P can't be sacrificed. Because if it is... everything else will fail. Being Google they are probably prideful enough to think their servers could never have an outage. Which yes, I agree with you, that is a very scary claim.

The "choose two" of the CAP theorem is a bit misleading. By creating a distributed system, you've chosen P. So it's really choose one: A or C.

Re: Introducing Cloud Spanner, a Global Database Service

#57
post #38

> Unlike most wide-area networks, and especially the public internet, Google controls the entire network and thus can ensure redundancy of hardware and paths, and can also control upgrades and operations in general I know this is a single system, but I'll still say it. This seems like another step in a scary trend for our internet.

Why is it a scary trend that Google has made their part of the internet more resilient?

The parent comment author seems to be disturbed by the phrase "controls the entire network." Setting aside his unwarranted paranoia, it does make me wonder which organization has the largest and most reliable corner of the internet. Google certainly qualifies by sheer volume of hardware and network infra.

Re: Introducing Cloud Spanner, a Global Database Service

#58
post #49

What is TrueTime really? Are their Distributed Systems 'sharing a global clock'?

From the Spanner paper:

> The underlying time references used by TrueTime are GPS and atomic clocks. TrueTime uses two forms of time reference because they have different failure modes... TrueTime is implemented by a set of time master machines per datacenter and a timeslave daemon per machine. The majority of masters have GPS receivers with dedicated antennas; these masters are separated physically to reduce the effects of [GPS] antenna failures, radio interference, and spoofing. The remaining masters (which we refer to as Armageddon masters) are equipped with atomic clocks. An atomic clock is not that expensive: the cost of an Armageddon master is of the same order as that of a GPS master.

Source: https://static.googleusercontent.com/media/research.google.c...

Re: Introducing Cloud Spanner, a Global Database Service

#59

> Unlike most wide-area networks, and especially the public internet, Google controls the entire network and thus can ensure redundancy of hardware and paths, and can also control upgrades and operations in general I know this is a single system, but I'll still say it. This seems like another step in a scary trend for our internet.

I am an employee, and have my biases, but I’ll always prefer a customer's data stay on our backbone and not be passed through the public internet. Our customers also prefer it, and it's not something other Cloud providers can fully cover.

Re: Introducing Cloud Spanner, a Global Database Service

#60
post #34

> clients can do globally consistent reads across the entire database without locking How is this possible across data centres? Does it send data everywhere at once? Seems too good to be true of course but if it works and scales it might be worthwhile just not having to worry about your database scaling? Still I don't believe it ;-) EDIT: further info... > Spanner mitigates this by having each member be a Paxos group…

> In terms of CAP, Spanner claims to be both consistent and highly available despite operating over a wide area, which many find surprising or even unlikely. The claim thus merits some discussion. Does this mean that Spanner is a CA system as defined by CAP? The short answer is “no” technically, but “yes” in effect and its users can and do assume CA. The purist answer is “no” because partitions can happen and in fact…

I would expect more from Brewer.

"CA except when there are partitions" is CP. It's not "effectively CA".

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