Re: Prefered Types
От | Зотов Роман |
---|---|
Тема | Re: Prefered Types |
Дата | |
Msg-id | 4DC05813.80509@oe-it.ru обсуждение исходный текст |
Ответ на | Re: Prefered Types (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: Prefered Types
(Alvaro Herrera <alvherre@commandprompt.com>)
|
Список | pgsql-hackers |
03.05.2011 23:06, Tom Lane пишет: > I wrote: >> Alvaro Herrera<alvherre@commandprompt.com> writes: >>> The interesting discussion is what happens next. To me, this is all >>> related to this previous discussion: >>> http://archives.postgresql.org/pgsql-hackers/2010-09/msg00232.php >> Yeah, there doesn't seem like much point unless we have a clear idea >> what we're going to do with the change. > BTW, it occurs to me to wonder whether, instead of making types be more > or less preferred, we should attack the issue from a different direction > and assign preferred-ness ratings to casts. That seems to be more or > less the direction that Robert was considering in the above-linked > thread. I'm not sure it's better than putting the ratings on types --- > in particular, neither viewpoint seems to offer a really clean answer > about what to do when trying to resolve a multiple-argument function > in which one possible resolution offers a more-preferred conversion for > one argument but a less-preferred conversion for another one. But it's > an alternative we ought to think about before betting all the chips on > generalizing typispreferred. > > Personally I've always felt that the typispreferred mechanism was a bit > of a wart; changing it from a bool to an int won't improve that, it'll > just make it a more complicated wart. Casts have already got a > standards-blessed notion that some are more equal than others, so > maybe attaching preferredness ratings to them will be less of a wart. > Not sure about it though. > > regards, tom lane > Now I use this change i manual change preferring of some types (in system tables) and it give me possibility not add some functions clones. I don`t know how (and i think i have no right) to change syntax to use this feature. After many times thinking i find another way to resolve my problem: if function only one we must use Assignment cast rules. But it can help only for me... thats why i think we can change rules to calc prefer like assignment rules have lesser priority, but available. but here we can see problem like F(smallint) F(integer) but call like F(float) i wouldn`t like to fail it. PS This patch needet, because in any case we must calc prefer more smartly, yes this patch is 1/10 of full solution, but it`s first step!!! -- С уважением, Зотов Роман Владимирович руководитель Отдела разработки ЗАО "НПО Консультант" г.Иваново, ул. Палехская, д. 10 тел./факс: (4932) 41-01-21 mailto: zotov@oe-it.ru
В списке pgsql-hackers по дате отправления: