Brent Ozar performs an experiment:
At the PGConf.dev, where Postgres developers get together and strategize the work they wanna do for the next version, I attended a session where Matthias van de Meent talked about changing the way Postgres stores columns. As of right now (Postgres 17), columns are aligned in 8-bit intervals, so if you create a table with alternating columns:
Read on to see an example, and then Brent performs a test to see how SQL Server handles this scenario. The comments also mention that at least older versions of Oracle behaved like Postgres.