Re: wip: functions median and percentile

Поиск
Список
Период
Сортировка
От Pavel Stehule
Тема Re: wip: functions median and percentile
Дата
Msg-id AANLkTimso=jVibBgQ6Y4gnzOkWb9miOXnhNGy_5UtGJf@mail.gmail.com
обсуждение исходный текст
Ответ на Re: wip: functions median and percentile  (David Fetter <david@fetter.org>)
Ответы Re: wip: functions median and percentile  ("Kevin Grittner" <Kevin.Grittner@wicourts.gov>)
Список pgsql-hackers
2010/8/19 David Fetter <david@fetter.org>:
> On Thu, Aug 19, 2010 at 12:12:12PM -0500, Kevin Grittner wrote:
>> David Fetter <david@fetter.org> wrote:
>>
>> > Median may be useful, but we pretty much can't just call it
>> > "median." Instead, we need to call it something like "left_median"
>> > or "arithmetic_median."
>>
>> I think it would be reasonable, and perhaps preferable, to use just
>> "median" for the semantics described in most dictionaries -- for
>> example, this:
>>
>> http://www.merriam-webster.com/dictionary/median
>>
>> If you do a google search for "median" and poke around, you'll find
>> many places where this is the only definition mentioned; the others
>> seem to be rather infrequently used.  Why not make the commone usage
>> convenient?
>
> The reason not to is the same reason that MEDIAN doesn't appear in the
> SQL standard, namely that what's common in one field is wrong in
> another.

I think some else. The reason can be more simple - implementation of
median is significantly harder  then other aggregates.

I looked there and Oracle11g use "median" in common sense.

Regards

Pavel Stehule
>
> Cheers,
> David.
> --
> David Fetter <david@fetter.org> http://fetter.org/
> Phone: +1 415 235 3778  AIM: dfetter666  Yahoo!: dfetter
> Skype: davidfetter      XMPP: david.fetter@gmail.com
> iCal: webcal://www.tripit.com/feed/ical/people/david74/tripit.ics
>
> Remember to vote!
> Consider donating to Postgres: http://www.postgresql.org/about/donate
>


В списке pgsql-hackers по дате отправления:

Предыдущее
От: Pavel Stehule
Дата:
Сообщение: Re: wip: functions median and percentile
Следующее
От: David Fetter
Дата:
Сообщение: Re: wip: functions median and percentile