03.05.2011 23:06, Tom Lane пишет:
I wrote:
Alvaro Herrera<alvhe...@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: zo...@oe-it.ru
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
