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Not necessarily. You can SET ROLE at beginning of transaction and DISCARD afterward. This is what postgraphile and postgrest do, for example.

postgrest actually does a `SET LOCAL ROLE`(transaction scoped, so no need to DISCARD), but yes, that's the gist of it.

Oh cool, I didn't know that. Good to learn!

This absolutely isn't required; I think you might be getting confused with RBAC rather than RLS. Handy infosheet: https://learn.graphile.org/docs/PostgreSQL_Row_Level_Securit...

You can just change the user for every query.