backend(照你nestjs+mysql+docker所講)其實分開幾個大類
1. application logic
2. DB (schema design + optimization)
3. Deployment
第一part就係你隨便用一個framework都好,你都可以寫API
efficient定唔efficient係一回事,你嘅usage會唔會去到efficiency影響到你嘅app logic又係令一回事。正常嚟講,如果你想學嘢,你可以如果nodejs寫完再用golang練習一次。咁第時要你用其他lang到可以應用到d transferrable skills
第二part,DB,我個人認為SQL界就postrgres,NoSql就Mongo係最多人用嘅production grade DB,唔會有死。99%嘅人都唔會係因為DB差而query慢,只會係ORM (講緊你啊Prisma)或者skill issue而有效能樽頸位,所以揀Postgres/Mongo都一定無問題。近年mongo已經support好多relation相關嘅功能(留比熟mongo嘅師兄補充下),你用得盡個DB再投訴都未遲
第三係devop。如果你係細project,自己push完自己去個ec2 pull+build+pm2 deploy並無不可,但當你開始考慮到zero downtime就需要用AWS ECS / k8s / digitalocean
其實個人認為k8s真係言過其實(雖然你無問,但backend+infra好多都想學k8s),普通ecs/digital app platform已經可以做到無縫update,我d freelance都係開心使用中
利申返工用左兩年k8s,已考cka(78/100) (公司無資助)+ clad(90/100) (公司無資助),希望大家唔好入k8s坑
結語
Start with anything (literally really anything) until you reach the limit (which is very unlikely). Congratulations if you really reach the limits.