= is not always defined as equality is bad

Поиск
Список
Период
Сортировка
От Zeugswetter Andreas DBT
Тема = is not always defined as equality is bad
Дата
Msg-id 219F68D65015D011A8E000006F8590C60F2525@sdexcsrv1.sd.spardat.at
обсуждение исходный текст
Ответы Re: [HACKERS] = is not always defined as equality is bad  (Bruce Momjian <maillist@candle.pha.pa.us>)
Список pgsql-hackers
Vadim wrote:
> but this will be "known bug": this breaks OO-nature of Postgres,
because of
> operators can be overrided and '=' can mean  s o m e t h i n g (not
equality).
> Example: box data type. For boxes, = means equality of _areas_ and =~
> means that boxes are the same ==> =~ ANY should be used for IN.

Ok, here I think there should be a restriction to have the = operator
always be defined as equality operator. Because in the long run it will
be hard
to write equality restrictions.   a = a1 and b =~ b1 and c +*#~ c1.
Also =, >, <, >= and the like will allways be candidates for use by the
optimizer
(boolean math to simplify restriction or to make an existing index
usable could be used).

I vote for:  = must always be defined as equality in user defined types.

(if such comparison is not possible for a special type the = should not
be defined for it)
I therefore also suggest changing the box ops =~ to = and the area = to
some other sign.

Andreas

В списке pgsql-hackers по дате отправления:

Предыдущее
От: The Hermit Hacker
Дата:
Сообщение: Re: New pg_pwd patch and stuff
Следующее
От: "Vadim B. Mikheev"
Дата:
Сообщение: Re: [HACKERS] Re: subselects