Well, this was maybe a bit entry level description.
Q: "databases are often the worst-performing part of the tech stack" - compared to what? nginx throughput? I find this to be a bit of a strange view, surely business logic is always the slowest part of the tech stack
Q: "What happens if that int should actually be a float?" - how often do you actually need to run migrations versus just extending the data? From my end, I have a small idempotent database schema-maintaining tool, and if I need a new column or a new table there's no need for a migration, and you know your whole stack will interact with the new schema or old schema identically assuming you set sane defaults etc. I've built a lot of medium-quality low-traffic apps so I'm yet to encounter a real-world case where a migration wasn't just bad planning
Q: "databases are often the worst-performing part of the tech stack" - compared to what? nginx throughput? I find this to be a bit of a strange view, surely business logic is always the slowest part of the tech stack
Q: "What happens if that int should actually be a float?" - how often do you actually need to run migrations versus just extending the data? From my end, I have a small idempotent database schema-maintaining tool, and if I need a new column or a new table there's no need for a migration, and you know your whole stack will interact with the new schema or old schema identically assuming you set sane defaults etc. I've built a lot of medium-quality low-traffic apps so I'm yet to encounter a real-world case where a migration wasn't just bad planning