Step by Step

A/C: 看Doc 理解各個步驟的真正含義，summarize & 簡短總結成關鍵詞 so that可以在每個system里面套用
ETA 8號

TinyURL

A/C: TBD
ETA 10號

Pastebin

A/C: TBD
ETA 12號

System Design Interviews: A step by step guide

Step 1: Requirements clarifications

搞清楚：
包含哪些功能
包不包括video or photos
only focus on the back-end or both back-end and front-end?

Step 2: System interface definition

目的：
establish the exact contract expected from the system
確保requirements 理解正確

Step 3: Back-of-the-envelope estimation（粗略估計）

問問題 --> estimate ==> will help (later) scaling, LB and caching.

問題example:

• scale (如多少tweets posted, 多少tweets viewed, 多少timeline generation等)
• 多大storage
• network bandwidth --> decide how to manage traffic and balance load among servers

Step 4: Defining data model

identify various entities of the system
--> NoSQL or SQL
What kind of block storage should we use to store photos and videos?

Step 5: High-level design

畫block diagram with 5~6 boxes 來表示system的components

Twitter example:

high-level components

并且要：根據(jù)A需求，我們要用B來handle。
例子：根據(jù)有大量read tweets，我們要用separate servers來handle。

Step 6: Detailed design

選一兩個dig deeper。根據(jù)interviewer 的feedback 詳細解釋哪一部分。

應該always提供不同的approches，并且比較他們的pros and cons，并說為什么最后選擇這種?？紤]tradeoff。

可能涉及：

• database partition
• handle hot user
• optimize (LB, cache, etc.)

Step 7: Identifying and resolving bottlenecks

討論bottlenect，越多越好，并提供不同approches to mitigate them

• single point failure(single point failure impacts the whole system) （failover?）
• replica?
• monitoring & alerts for performance?