Re: [GENERAL] Performance of full outer join in 8.3

Поиск
Список
Период
Сортировка
От Greg Stark
Тема Re: [GENERAL] Performance of full outer join in 8.3
Дата
Msg-id 4136ffa0904180539p64e3afc5s6ce52a371d2d3387@mail.gmail.com
обсуждение исходный текст
Ответ на Re: [GENERAL] Performance of full outer join in 8.3  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: [GENERAL] Performance of full outer join in 8.3  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-hackers
On Sat, Apr 18, 2009 at 1:32 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> I'm inclined to think that some sort of fuzzy examination of EXPLAIN
> output (in this example, "are there constant-comparison conditions in
> the relation scans?") might do the job, but I'm not sure how we'd
> go about that.

If we just removed all the costs and other metrics from the explain
plan and verified that the plan structure was the same would you be
happy with that? It would still be work to maintain every time the
planner changed.

I suppose if we had explain-to-a-table then we could run explain and
then run an sql query to verify the specific properties we were
looking for.

A similar thing could be done with xml if we had powerful enough xml
predicates but we have a lot more sql skills in-house than xml.

-- 
greg


В списке pgsql-hackers по дате отправления:

Предыдущее
От: Tom Lane
Дата:
Сообщение: Re: [GENERAL] Performance of full outer join in 8.3
Следующее
От: Heikki Linnakangas
Дата:
Сообщение: Re: [PATCH] unalias of ACL_SELECT_FOR_UPDATE