On Sat, Nov 11, 2017 at 04:34:31PM +0100, Dmitry Dolgov wrote: > > > > > > Here isAssignment is unused variable, so it could be removed. > > > > In this case I disagree - the purpose of these examples is to show > everything > > you can use. So I just need to come up with some example that involves > > `isAssignment`. > > I've incorporated this variable into the tutorial.
Great. I think users will know how to use isAssignment now. > > I have a little complain about how ExprEvalStep gets resvalue. resvalue is > > assigned in one place (within ExecEvalSubscriptingRefFetch(), > > ExecEvalSubscriptingRefAssign()), resnull is assigned in another place > > (within jsonb_subscript_fetch(), jsonb_subscript_assign()). > > Hm...I'm afraid I don't get this. `resnull` is never assigned inside > `jsonb_subscript_fetch` or `jsonb_subscript_assign`, instead it's coming > from `ExecInterpExp` as `isnull` if I remember correctly. Are we talking > about > the same thing? No, I meant ExprEvalStep struct. For example, within ExecEvalSubscriptingRefFetch() you assign *op->resvalue but *op->resnull is leaved as unchanged: > ExecEvalSubscriptingRefFetch(ExprState *state, ExprEvalStep *op) > ... > *op->resvalue = FunctionCall2(op->d.sbsref.eval_finfo, > PointerGetDatum(*op->resvalue), > PointerGetDatum(op)); For jsonb *op->resnull is changed within jsonb_subscript_fetch() for arrays within array_subscript_fetch() (which are called by ExecEvalSubscriptingRefFetch()): > return jsonb_get_element(DatumGetJsonbP(containerSource), > sbstate->upper, > sbstate->numupper, > step->resnull, > /* step->resnull is changed within jsonb_get_element() */ > false); It is not critical, but it may be good to change them in one place. > > In this version of the patch I also improved NULL handling, you can see it > in > the tests. New tests passed. -- Arthur Zakirov Postgres Professional: http://www.postgrespro.com Russian Postgres Company
