HTTP idempotence is only concerned with effects of the request, not the result returned.
RFC7231:
> A request method is considered "idempotent" if the intended effect on the server of multiple identical requests with that method is the same as the effect for a single such request.
note the on the server.
(or old specs, 2616: Methods can also have the property of "idempotence" in that (aside from error or expiration issues) the side-effects of N > 0 identical requests is the same as for a single request. - again, side-effects, not responses)
How does a read-only database query being repeated cause a change in the database?
RFC7231:
> A request method is considered "idempotent" if the intended effect on the server of multiple identical requests with that method is the same as the effect for a single such request.
note the on the server.
(or old specs, 2616: Methods can also have the property of "idempotence" in that (aside from error or expiration issues) the side-effects of N > 0 identical requests is the same as for a single request. - again, side-effects, not responses)
How does a read-only database query being repeated cause a change in the database?