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by phrotoma 206 days ago
I am extremely Not A Database Person but I understand that the rationale for Kubernetes adopting etcd as its preferred data store was more about its distributed consistency features and less about query throughput. etcd is slower cause it's doing RAFT things and flushing stuff to disk.

Projects like kine allow K8s users to swap sqlite or postgres in place of etcd which (I assume, please correct me otherwise) would deliver better throughput since those backends don't need to perform consenus operations.

https://github.com/k3s-io/kine
3 comments
dijit 206 days ago
You might not be a database person, but you’re spot on.

A well managed HA postgresql (active/passive) is going to run circles around etcd for kube controlplane operations.

The caveat here is increased risk of downtime, and a much higher management overhead, which is why its not the default.

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travem 206 days ago
There are also distributed databases that use RAFT but can still scale while delivering distributed consensus don’t is not a challenge that can’t be solved. For example, TiDB handles millions of QPS while delivering ACID transactions, e.g. https://vivekbansal.substack.com/p/system-design-study-how-f...
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Sayrus 206 days ago
GKE uses Spanner as an etcd replacement.
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ZeroCool2u 206 days ago
But, and I'm honestly asking, you as a GKE user don't have to manage that spanner instance, right? So, you should in theory be able to just throw higher loads at it and spanner should be autoscaling?
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DougBTX 206 days ago
Yes, from the article:

> To support the cluster’s massive scale, we relied on a proprietary key-value store based on Google’s Spanner distributed database... We didn’t witness any bottlenecks with respect to the new storage system and it showed no signs of it not being able to support higher scales.

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ZeroCool2u 206 days ago
Yeah, I guess my question was a bit more nuanced. What I was curious about was if they were fully relying on normal autoscaling that any customer would get or were they manually scaling the spanner instance in anticipation of the load? I guess it's unlikely we're going to get that level of detailed info from this article though.
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