https://www.youngju.dev/blog 천천히 올바르게. AI Researcher & DevOps Engineer Youngju's tech blog. GPU/CUDA, LLM, MLOps, Kubernetes AI workloads, distributed training, and data engineering. ko fjvbn2003@gmail.com (Youngju Kim) fjvbn2003@gmail.com (Youngju Kim) Tue, 23 Jun 2026 00:00:00 GMT https://www.youngju.dev/blog/2026-06-23-cap-theorem-no-handwaving.en https://www.youngju.dev/blog/2026-06-23-cap-theorem-no-handwaving.en The popular "pick two of three" summary is wrong. This post pins down exactly what each of the three letters means, why in practice you only choose between C and A when a partition happens, why PACELC is the more complete picture, and where real systems like Dynamo and Spanner actually stand. Tue, 23 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) distributed-systemsdatabasestheory https://www.youngju.dev/blog/2026-06-23-cap-theorem-no-handwaving.ja https://www.youngju.dev/blog/2026-06-23-cap-theorem-no-handwaving.ja 「三つのうち二つを選ぶ」という定番の説明は間違いです。三つの文字がそれぞれ何を厳密に意味するのか、なぜ実際にはパーティションが起きたときだけCとAのあいだで選ぶのか、なぜPACELCがより完全な絵なのか、そしてDynamoやSpannerといった実システムがどこに立っているのかを、ごまかさずに押さえます。 Tue, 23 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) distributed-systemsdatabasestheory https://www.youngju.dev/blog/2026-06-23-cap-theorem-no-handwaving https://www.youngju.dev/blog/2026-06-23-cap-theorem-no-handwaving "셋 중 둘을 고른다"는 흔한 설명은 틀렸습니다. CAP의 세 글자가 각각 무엇을 뜻하는지, 왜 실제로는 파티션이 났을 때만 C와 A 사이에서 선택하는지, PACELC이 왜 더 완전한 그림인지, 그리고 Dynamo와 Spanner 같은 실제 시스템이 어디에 서 있는지를 손짓 없이 짚습니다. Tue, 23 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) distributed-systemsdatabasestheory