How do you find it when you scale it up to every table, every query?
It scales just fine depending of course on the usual stuff - load pattern etc. If you want really high scalability you should be using something like clickhouse anyway.
Edit to add: the rationale behind having separate intraday and daily time series tables in those systems is the type of the value and as of timestamps is different (in one its a date, in one its a datetime), and storing dates as datetimes is a rich source of bugs.
I agree a special database shouldn't be necessary at all, and instead, convenient syntax for immutable DML and temporal support should be built into Postgres already. But short of a miracle it will probably take a new ('special') database in order for Postgres to evolve in response. Therefore, in the meantime, we believe there's a gap in the market for organisations who value the 'safety' (foolproof complexity reduction) that native bitemporality in a database can offer above the raw query performance offered by existing update-in-place databases: https://xtdb.com/blog/but-bitemporality-always-introduces-co...