Re: No merge sort?

Поиск
Список
Период
Сортировка
От Taral
Тема Re: No merge sort?
Дата
Msg-id 20030315040703.GA3313@taral.net
обсуждение исходный текст
Ответ на Re: No merge sort?  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-hackers
On Fri, Mar 14, 2003 at 10:43:30PM -0500, Tom Lane wrote:
> Sure.  That's why we have a planner that distinguishes between startup
> cost and total cost, and interpolates when a LIMIT is involved.  But
> if this mergesort idea only helps for small-limit cases, that's another
> restriction on its scope of usefulness...

I don't think so, since even in the non-limit case it avoids having to
do a full sort if the number of initial streams is finite and small (as
in the case I demonstrated), reducing time complexity to O(N).

--
Taral <taral@taral.net>
This message is digitally signed. Please PGP encrypt mail to me.
"Most parents have better things to do with their time than take care of
their children." -- Me

В списке pgsql-hackers по дате отправления:

Предыдущее
От: Tom Lane
Дата:
Сообщение: Re: No merge sort?
Следующее
От: Tom Lane
Дата:
Сообщение: Re: [INTERFACES] Upgrading the backend's error-message infrastructure