---
# System prepended metadata

title: Interview Note
tags: [interview]

---

# Interview Note

## Shawn Ou Yang
### Question
```
## system design
### design a chat service
- how to check msg deliver sucessful
- how to handle 0.5-1M connection 
## Lambda
### How to desing a asynchronous invocation?
### How to optimize?
- memory
- cold start
  - prewarm
  - minimize package size
### Docker image or zip different?
### How to invoke lambda a period of time?
## HTTP
### CSP
### How to reduce data transfer by Http header?
### Session/token base explain? pros/cons
## RDB
### CTE
### partition
### two table product,order. table order have a FK with product's id, plz how to produce N+1 issue and how to avoid ?
### what is isolatoin 4 level? what time you should use "serializable"?
## Redis(should we ask?)
### what is redis's eviction policy? what's different?
### How would you use Redis as a distributed lock system? (Setnx)
###
## infra
### How to resolve a drift between CloudFromation resource's state and actual resource state?
### A diff version with lambda.
### zero downtime to migrate resource.
### design network's subnet for your service. Why? And if it need cross region, how to do?
```
### Response note
太貴 why? how much? 架構改善得過程
tw tai jp

log trace restful api? how to authrize? token jwt by user
ECS -> k8s
APi serverless non devops, cost concern.
lambda database issue. RDS proxy, management issue, routing issue, cold start(event bridge interval invocation). 

RDB licesne .. so postgres
nosql, RDMS diff not goood. large traffic issue. 
CTE, not know
parition, know not use too much
N+1, avoid response
RDS skill is not enough, however just for general operation 

Http traffic reduce ? drop unnecessary cookie, gzip
cache not know
cookie-session and token | He not know mechanism fully. 

test - what is test plan? feature not lock down requirement. 

individual plan: certifacte, speaker

what is your team/crop value? Addressing the problem from different perspectives,
strong communication.

product < technical | ?? why make money more important...however I can not feel he is hard core people
### Insight
|Name|Score|Desc
|---|---|---
|HTML|5|The mechanism is not know fully
|DB|4|the middle level skill is much weak. like CTE, N+1 concept...however he has ever use function and store procedure.
|System Design|-|He lacks experience in designing large-scale systems, or you could say he has done little exploration in this area. This part is completely out of consideration.
|cloud|7| aws network and iac much good, know blue/green deployment. lambda experince is also excellent.
|Cloud Provider|6|His lambda experince has good knowlage.

### Evaluate
As his skill level, I can ensure his skill level is not a senior should have. So only can accept 12 level. He lacks substantial experience and has gaps in base knowledge. It's hard to trust him as a project owner to handle tasks. Although his communication is relatively good and pleasant, he simply can't meet the technical requirements.
## Leamon
### Insight

|Name|Score|Desc
|---|---|---
||6|He know how to optimized SQL, patition and trigger usage.
|System Design|8|- Solved distribution service keeping consistency<br>- Solved service asynchronize task design <br>- good experience on micro service mesh.<br>- Large data and project experience, can consider throughput and io limitaion. <br>- More practice on ETL design
|CICD|7| good acknowledge on jenkins. he can modify/build cicd flow.
|Cloud Provider|6|- S3/lambda, good knowlage.


### Impression 

Certain level of experience in handling distributed data consistency. adequate optimization skills and practical experience in handling large/big data in both RDB and NoSQL databases. He is capable of independently designing and architecting systems on the AWS platform, showcasing considerable experience in overall system design. experience in integrating multiple languages, including not only Node.js but also Python and Java.

## Simon
### Insight

|Name|Score|Desc
|---|---|---
|RDB|7|He know how to optimized SQL, patition and trigger usage.
|System Design|8|- Solved distribution service keeping consistency<br>- Solved service asynchronize task design <br>- good experience on micro service mesh.<br>- Large data and project experience, can consider throughput and io limitaion. <br>- More practice on ETL design
|CICD|7| good acknowledge on jenkins. he can modify/build cicd flow.
|Cloud Provider|6|- S3/lambda, good knowlage.


### Impression 

Certain level of experience in handling distributed data consistency. adequate optimization skills and practical experience in handling large/big data in both RDB and NoSQL databases. He is capable of independently designing and architecting systems on the AWS platform, showcasing considerable experience in overall system design. experience in integrating multiple languages, including not only Node.js but also Python and Java.

## Sun
small team
divide requirement(?? how to define your known's system)


- subscription system design (keep transaction)
- common notification system

## Barry
borning from frontend,
1. graphQL, lambda set function, sqs, kenisis
2. mysql, redis

db 用到多深入?
lambda, database connnection issue? pool
through put issue
how to protect your api?
我想要了解你之前做過的business logical


## Johnny
### tech

aws ses , internal sqs(internal even driven requirement)
使用AWS遇過最困難問題?
log service 
eks node issue

cognito不好用,甚麼好用?
interface

DB digtal ocean
K8s logg and routing...concern


graph cons
- performance issue
- cache layer

fluentd
- steam issue
M service
- rolling change
- M service by requirement
- cost?

personal development plan 
- communication
- code review
- 感染其他人?

even driven
- od log


PBAC system design
ABAC concept is must control
RBAC relate is alos having.



###`sd
`
## Ruby Lai
python
時區的問題resolve
rbac code base ->? which DB (ACL) 繼承
docker 
ecr 
MySql know ACID, how to use tarnsaction to keep data consistency
redis cache => race condition issue (good resolve)
elastic search for text search

nodejs lambda/apigateway
MySQL ec2 loadbalancer s3
know gree/blue deployment,
ec2 switch different dns record.

- Test design
order system
ratelimit, redis, 彈出page限制進入
確保dirty data issue用transaction
確認發出信件 message queue, worker處理
rabbitmq 沒用過? 我也不知道你怎麼做queue 


- provide value
good communication (before PM experince)
code review
share other tech

- why leave 
PM no tech, hope more code skill
developer兼職pm需要討論
準備很多家, 應該有拿offer了


### Insight

|Name|Score|Desc
|---|---|---
|RDB(postgres)||
|System Design||
|CICD         ||
|Cloud Provide||

### Concern

### Impression 


## Kent Lu
### Insight

|Name|Score|Desc
|---|---|---
|RDB(postgres)|7|know how to optimized SQL, patition and trigger usage.
|System Design|7|- Solved race condition issue(recieve event update same data record)<br>- Solved queue debonce issue(socket send command to client)<br>-  Explain status shadow design<br>- Device to server connection mechanism with websocket<br>- Good for API knownlage. Divde API for different service, little micro service.<br>- program with java previously. he can help review code with android, cause he knows the lifecycle.
|CICD|8| excellent on jenkins. however he built all cicd flow.
|Cloud Provide|7|- S3, good knowlage. A case for application management upload request, made a external onetimes link to saving traffic.<br>- ECS, great knownlage. Thier service all built on ecs, he almost know ecs key point.

### Concern

- Not enough real experiance on Huge/big traffic issue.
- Thier DM product's customer is insufficient. Missing consider with throughput issue, scaling warm up...
- CICD integrate with shell and aws sdk. He does not have too much exprience  with IaC tool.

### Impression 

His team have 3 backend, 3 devops, 2 frontend.(I remember).
He is very like "Angle" as three years ago. he can complete design/plan/develop/ by himself. Knownlage is focus on device management and android.

**Note: Most his cloud technical skill is similar our team.**






###### tags: `interview`