Jim Finnerty <jfinnert@xxxxxxxxxx> writes: > Great example, David. The planner can detect whether a SELECT statement > contains a volatile function, and can disable the proposed redundant > inner-join optimization in that case. > If necessary, the planner could also check that the FK constraint is not > DEFERRED, but if there are no volatile functions and the SELECT statement > can't see an inconsistent state created by any other transaction, I think > that just checking for volatile functions and not being inside a DML > transaction would be sufficient. I don't think you're thinking nearly hard enough about what would break this. The planner does not have much insight into the context a statement is being used in (e.g. whether we're inside some kind of PL function). Nor does it get to make assumptions about whether the plan will be used inside a transaction block or not. regards, tom lane
