CRDTs: The Hard Parts

Martin Kleppmann · 90.4K views · 2020-07-06 · 1:10:10

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Overview

Martin Kleppmann surveys current research on CRDTs, the algorithms for merging concurrent edits across offline replicas. He covers the hard parts such as rich text, moves and merge results that are technically correct but poor.

On Hacker News

Recommended as an excellent first education on CRDTs and their limits.

Recommended by 3 HN people across 3 months · HN mentions 2020–2024

Topics

Distributed systems Algorithms & data structures

What people said

rkangel · 2021-01 · Strong recommendation
The author is a researcher on distributed systems. I found this video from him to be an excellent first education on CRDTs, how they work, what they're good for and what they aren't (yet) good for: [VIDEO]
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williamstein · 2024-12 · Recommendation
What they claim is that if all editing stops, then after a period of time everybody will be looking at the SAME document. This is what is meant by "eventual consistency". Achieving this in general is indeed a difficult problem, but (some of) these algorithms do solve it, though it can be tricky to correctly prove that they do. I agree that it is not possible to ensure that the document everybody is looking at is what they actually wanted it to be. However, there are some options for what happens, where some results may be technically correct -- we are all looking at the same thing -- but obviously really bad. This beautiful talk has some examples: [VIDEO]
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iamwil · 2024-01 · Recommendation
Ah, I'll put it in as a note in the beginning. You can see a more basic introduction in a previous post I wrote: [LINK] [LINK] Here's some introductory material I found helpful: - [An interactive intro to CRDTs]( [LINK] ) - [An introduction to state-based CRDTs]( [LINK] ) - [CRDTs for non-academics]( [LINK] ) - [CRDT: The Hard Parts]( [VIDEO] ) - [Readings in CRDTs]( [LINK] ) - [crdt.tech]( [LINK] )
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Sources

Video by Martin Kleppmann, played through YouTube.

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