Thomas Hallgren <thhal(at)mailblocks(dot)com> writes:
> Ok, now I understand. Thanks for the explanation. I guess that if
> read_only is set to true and an attempt is made to execute a plan that
> has side effect, that will cause an ERROR?
Right, it'll bounce anything except a SELECT query. (This test is not
watertight; consider SELECT nextval() ... but on the other hand that's a
non-transactional operation that does not care about snapshots anyway.)
regards, tom lane