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Reminder that AWS Aurora claims to have broken the CAP theorem. The literature doesn’t clarify whether they are consistent or available, and when you ask AWS di
by slau 3y ago
Reminder that AWS Aurora claims to have broken the CAP theorem. The literature doesn’t clarify whether they are consistent or available, and when you ask AWS directly, they tell you the CAP theorem isn’t relevant due to the way Aurora is built.
They claim 99.99% availability or whatever the figure is, that it’s self healing, allows up to 2 replicas to be down for write availability and 3 replicas to be down for read availability. They promise “millisecond consistency”, whatever that even means.
Some of the blogs mention that they use distributed state to extract slivers of consistency across the nodes, which is just scary stuff to hear.
I’m seeing more and more usage of Aurora due to the magical component it offers, but I can’t wrap my head around what it’s actually supposed to be, and what the failure model is, like I can with RDS PG and MySQL.
- asylteltine 3y agoCan’t you bypass CAP if you just have a ton of compute in the background handling all of these tasks in real time? Aurora isn’t just some binary running on ec2 it’s probably 10 different things going on
- slau 3y agoCAP is a property of any distributed system. You have to tolerate P (considering it’s distributed), so you can only be CP or AP. CP means you can’t be available, meaning your system will stop replying to queries. AP means you’re always available, but you could receive stale data when querying. It’s irrelevant whether it’s a single binary running on EC2 or a billion services working in unison. It’s a property of the system.
- deleted 3y ago[deleted]
- candiddevmike 3y agoAWS should show us the Jepsen or GTFO
- zokier 3y agoIsn't Aurora similar to Googles Spanner in this regard, giving pretty much same characteristics? https://cloud.google.com/blog/products/databases/inside-cloud-spanner-and-the-cap-theorem https://cloud.google.com/blog/products/databases/inside-clou... https://news.ycombinator.com/item?id=15923507 https://news.ycombinator.com/item?id=15923507
- wmfiv 3y agoI've not seem them claim to have broken CAP. AWS is quite an academic organization I think it'd be quite unlikely for them to say something like that. They do actually provide quite a lot of detail about Aurora storage this works. This 2019 reinvent talk gets pretty deep into the weeds. https://www.youtube.com/watch?v=uaQEGLKtw54 https://www.youtube.com/watch?v=uaQEGLKtw54 https://d1.awsstatic.com/events/reinvent/2019/REPEAT_Amazon_Aurora_storage_demystified_How_it_all_works_DAT309-R.pdf https://d1.awsstatic.com/events/reinvent/2019/REPEAT_Amazon_...
- belter 3y ago"Amazon Aurora: Design Considerations for High Throughput Cloud-Native Relational Databases" - https://assets.amazon.science/dc/2b/4ef2b89649f9a393d37d3e042f4e/amazon-aurora-design-considerations-for-high-throughput-cloud-native-relational-databases.pdf https://assets.amazon.science/dc/2b/4ef2b89649f9a393d37d3e04...