UML class diagram: Aggregation VS Composition

https://small-stepping.tistory.com/561 시간날때 정리하기 -> java 예제 코드까지 쓰면 이해 빠름 MVC MVP MVVM

Write-Through Let's start with the simplest writing policy: Write-Through. In this approach, when data needs to be updated, we write it to both the cache and the main database simultaneously. Only when both writes are complete does the system confirm the update. This policy ensures that the cache and database stay perfectly synchronized, making it ideal for systems where data consistency is critical, like financial applications or inventory management. But Write-Through has a significant drawback. Every write operation must wait for both the cache and database updates to complete, which can make write operations slower. Write-Back To address the performance limitation of Write-Through, some systems use Write-Back (also called Write-Behind). With Write-Back, data is initially written only to the cache, and the system immediately confirms the update. The modified data is written to the database later, usually in batches. This makes write operations much faster since they don't have to wait for the slower database write. Write-Back is perfect for systems that need high write performance, like real-time analytics or gaming applications. ...

DB Replication https://ysiksik.github.io/elegant-tekotok/2022-12-01-ANGIE-DB-Replication/ 언제 사용? Case 1 해결책 DB 백업 사용자가 요청을 보냈는데 데이터베이스가 응답하지 않는다. 설상가상 다시 재가동도 되지 않는다. 레플리카 서버를 소스서버로 승격시켜 사용할 수 있다. Case 2 해결책 write-read db 분리 요청 트래픽 증가 트랙픽의 부하 분산이 필요한 상황 스케일 업에도 한계가 있다. 소스 서버를 Write DB로 레플리카 서버를 읽기 전용인 Read DB로 사용해 부하를 해결할 수 있다. 주(master)-부(slave) 관계로 분리 master: 쓰기 연산 대상 slave: 읽기 연산 대상 장점 병렬 처리 가능한 query가 증가하여 성능 개선 서버 일부가 파괴되어도 데이터가 보존 → ACID의 영속성(Durability) 보장

https://www.linkedin.com/posts/gabag26_systemdesign-softwareengineering-codinginterview-activity-7287703050570371072-gaNt?utm_source=share&utm_medium=member_desktop 1. B-Trees vs LSM Trees: https://lnkd.in/gvNmyeUK 2. Database Replication: https://lnkd.in/gCS8Ydbk 3. SQL vs NoSQL databases: https://lnkd.in/g6ACc2hV 4. Consistent ...

Chapter 12 책의 그림들 12-8, 12-11, 12-12, 12-16, 12-17 여기다 시간날때 정리하기 https://universe-lee.tistory.com/191 Chat system can be divided to 3 parts : 1. stateless services(API server) 2. stateful services(Chat server with Websocket) 3. Thrid Party Integration (push notification) 채팅 서버: 클라이언트 간에 메시지 중계하는 역할 접속상태 서버(presence server): 사용자 접속 여부 ...