老猫的系统设计总结

找工作断断续续持续了快一年时间。有点拖拉。但是最终还是修成正果。拿到了狗脸软亚的offer。准备去脸家。
面完了自己也想写一个系统设计的总结，一来将来在找工作的时候有点参考，二来希望能帮到其他人。

貌似地里格式搞起来比较麻烦？我自己有一个文档。有时间我会慢慢优化，加一些东西。很多地方都写的比较简单。稍微搞好一点有机会在发出来让大家下载……

写的比较乱，有些描述也不见得准确。还有很多语法错误。请大家指正……谢谢

Overview: System
Typically, the system design question is backend focused.  That means the candidate does not need to consider the front-end structure.  For backend, a system typically has:
1.        A or a set of services, that provide required functions.
2.        A or a set of data stores, that host the static information.
3.        A or a set of cache, either sit in the service or as a centralized cache, that speed up the system.
In addition to the 3 parts, we typically have one or a set of load balancers to distribute the load to multiple servers.
All these pieces combine together and form a system.  System design questions test candidates’ understanding of all these pieces and the capability to use them.

Part 0: Collect Requirements
1.        System functional requirements
2.        Traffic size
3.        Data size

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Curated Interview Questions from Top Companies

Part 4: Datastore
First of all, discuss the table structure.  Table name, columns, info etc.  
Second, discuss the data volume.  How many data points, size of the data, how long to keep the data.
Third, which database to use?

Relational Database (MySQL, Oracle):
Relational Database will be suitable for small projects, or locations that require 100% CAP…

Cassandra:
Cassandra has quite a few benefits: a) no single point of failure.  B) read fast.  
Potential issue: a) update/delete a little slow as it needs to update/delete information from multiple nodes.  B) low consistency.  

H-Base:
H-Base is backed by Hadoop.  
Benefits: a) Consistency is high (it is a master-slave structure)  b) fast read, especially when fetching a handful records from a large quantity of data.  
Potential issue: a) needs a lot of expertise, including Hadoop, zookeeper (for service discovery), Hive (For query) etc.  It is not a simple system.

HDFS (Hadoop distributed file system):
It is used widely to store static data, such as pictures and videos.



补充内容 (2019-9-22 07:48):
发现有一个系统设计专区……管理员可不可以帮忙移过去？
谢谢

Some takeaways:

- MemCache are cache that sits in the application service. 之前还不知道。以为memcached vs redis就是一个没有file system backup, 一个有。
- HBase is Strong Consistency。脑海中所有NoSQL都是eventual consistency。 原来不是

请叫我热情老八 发表于 2019-9-22 08:57
感谢楼主的分享！ 想问下楼主，我猜楼主应该是社招， 社招的话 system design 是怎么准备的？

买了那个 [url=@Yun Zhang  https://www.1point3acres.com/bbs/thread-552194-1-1.html  这个帖子里也有grokking the system design interview，我们有affiliate link： https://www.educative.io/courses ... d=5749180081373184/]grokking the system design interview[/url]...
然后看帖
自己Google

prettyyyyyyyyyyyyyyyyy good

感谢楼主的分享！ 想问下楼主，我猜楼主应该是社招， 社招的话 system design 是怎么准备的？

感谢楼主分享 已加米

楼主方便讲讲是几年经验，什么方向么（后端/前端/全栈），之前在什么规模的公司工作么？

太太牛逼了，很精练，也很到位。谢谢。文科转码很受用。

gongchen 发表于 2019/09/22 11:21:48
感谢楼主分享 已加米

楼主方便讲讲是几年经验，什么方向么（后端/前端/全栈），之前在什么规模的公司工作么？

后端。在一个OTA混:-)公司不是很大，也就几百人吧。

谢谢楼主分享！！

好贴必须mark之，感谢lz！

谢谢楼主的分享。今天刚刚面了system design一脸懵逼