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) Mon, 29 Jun 2026 00:00:00 GMT https://www.youngju.dev/blog/2026-06-29-distributed-transactions-saga.en https://www.youngju.dev/blog/2026-06-29-distributed-transactions-saga.en Why the ACID that was easy inside one database falls apart across services, how two-phase commit works and where it breaks (coordinator, blocking, failure modes), the Saga pattern (choreography vs orchestration, compensating transactions), the outbox pattern that solves the dual-write problem, and what eventual consistency really means in practice. Transactions for the microservices era. Mon, 29 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) distributed-systemstransactionssaga https://www.youngju.dev/blog/2026-06-29-distributed-transactions-saga.ja https://www.youngju.dev/blog/2026-06-29-distributed-transactions-saga.ja 一つのデータベース内では簡単だったACIDが、なぜ複数サービスにまたがると崩れるのか、2フェーズコミットの原理と限界（コーディネータ、ブロッキング、障害モード）、Sagaパターン（コレオグラフィ vs オーケストレーション、補償トランザクション）、二重書き込み問題を解くアウトボックスパターン、そして結果整合性が実務で意味することまで。マイクロサービス時代のトランザクションを整理します。 Mon, 29 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) distributed-systemstransactionssaga https://www.youngju.dev/blog/2026-06-29-distributed-transactions-saga https://www.youngju.dev/blog/2026-06-29-distributed-transactions-saga 한 데이터베이스 안에서는 쉬웠던 ACID가 왜 여러 서비스에 걸치면 무너지는지, 2단계 커밋(코디네이터, 블로킹, 실패 모드)의 원리와 한계, Saga 패턴(코레오그래피 vs 오케스트레이션, 보상 트랜잭션), 이중 쓰기 문제를 푸는 아웃박스 패턴, 그리고 결과적 일관성이 실무에서 뜻하는 바까지. 마이크로서비스 시대의 트랜잭션을 정리합니다. Mon, 29 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) distributed-systemstransactionssaga https://www.youngju.dev/blog/2026-06-30-db-transactions-isolation.en https://www.youngju.dev/blog/2026-06-30-db-transactions-isolation.en What ACID actually guarantees, the four isolation levels (read uncommitted → serializable), the anomalies each one permits (dirty, non-repeatable, and phantom reads, plus write skew), MVCC, locking versus optimistic concurrency, SELECT FOR UPDATE, and why PostgreSQL and MySQL ship with different defaults. A practical tour of why transactions are hard and what they really protect. Tue, 30 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) databasestransactionsacid https://www.youngju.dev/blog/2026-06-30-db-transactions-isolation.ja https://www.youngju.dev/blog/2026-06-30-db-transactions-isolation.ja ACIDが実際に何を保証するのかから、四つの分離レベル（read uncommitted → serializable）、各レベルが許す異常（ダーティ・反復不能・ファントムリード、書き込みスキュー）、MVCC、ロックと楽観的並行制御、SELECT FOR UPDATE、そしてPostgreSQLとMySQLでデフォルトが違う理由まで。トランザクションがなぜ難しく、何を本当に守ってくれるのかを実践的に整理します。 Tue, 30 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) databasestransactionsacid https://www.youngju.dev/blog/2026-06-30-db-transactions-isolation https://www.youngju.dev/blog/2026-06-30-db-transactions-isolation ACID가 실제로 무엇을 보장하는지부터, 네 가지 격리 수준(read uncommitted → serializable), 각 수준이 허용하는 이상 현상(dirty·non-repeatable·phantom read, write skew), MVCC와 잠금·낙관적 동시성, SELECT FOR UPDATE, 그리고 PostgreSQL과 MySQL의 기본값 차이까지. 트랜잭션이 왜 어렵고 무엇을 지켜 주는지 실전 관점에서 정리합니다. Tue, 30 Jun 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) databasestransactionsacid