Not necessarily true. E.g. in PostgreSQL, the planner is free to evaluate predicates prior to imposing RLS constraints, so long as the functions in the predica

Not necessarily true. E.g. in PostgreSQL, the planner is free to evaluate predicates prior to imposing RLS constraints, so long as the functions in the predicate are marked LEAKPROOF [1]. (They aren't by default.) This is because UDFs can write to tables, and perform I/O in other ways depending on system configuration and security policy. Just because the UDFs are in WASM instead of one of the other UDF languages doesn't eliminate the need for a security system. (Aside -- curiously in PostgreSQL, the privilege system isn't even strong enough to prevent something as innocuous as e.g. reading a view owned by another user from dropping your own tables.) [1] https://www.postgresql.org/docs/15/sql-createpolicy.html#id-1.9.3.75.7 https://www.postgresql.org/docs/15/sql-createpolicy.html#id-...