Re: [HACKERS] What about LIMIT in SELECT ?

Поиск
Список
Период
Сортировка
От Terry Mackintosh
Тема Re: [HACKERS] What about LIMIT in SELECT ?
Дата
Msg-id Pine.LNX.3.95.981014130857.14397B-100000@terry1.acun.com
обсуждение исходный текст
Ответ на Re: [HACKERS] What about LIMIT in SELECT ?  ("Jeff Hoffmann" <jeff@remapcorp.com>)
Список pgsql-hackers
On Tue, 13 Oct 1998, Jeff Hoffmann wrote:

> >Hi, my 2 cents...
> >
> >I agree completely, LIMIT would be VERY usefull in web based apps, which
> >is all I run.  It does not matter to me if it is not part of a formal
> >standard.  The idea is so common that it is a defacto standard.
>
> i'm not familiar with mysql and using "LIMIT" but wouldn't this same effect
> be achieved by declaring a cursor and fetching however many records in the
> cursor?  it's a very noticeable improvement when you only want the first 20
> out of 500 in a 200k record database, at least.

Yes, while this is an improvement, it still has to do the entire query,
would be nice if the query could be terminated after a designated number
of rows where found, thus freeing system resources that are other wise
consumed.
I have seen web users run ridculous querys, like search for the
letter 'a', and it happens to be a substring search, now the box go'es ape
shit for 5 or 10 min.s while it basically gets the whole db as the search
result.  All this befor you can do a 'FETCH', as I understand FETCH, I
will need to read up on it.

Note that I do not have any databases that larg on my box, I was thinking
back to my VFP/NT experiances.

Have a great day
Terry Mackintosh <terry@terrym.com>          http://www.terrym.com
sysadmin/owner  Please! No MIME encoded or HTML mail, unless needed.

Proudly powered by R H Linux 4.2, Apache 1.3, PHP 3, PostgreSQL 6.3
-------------------------------------------------------------------
Success Is A Choice ... book by Rick Patino, get it, read it!


В списке pgsql-hackers по дате отправления:

Предыдущее
От: Bruce Momjian
Дата:
Сообщение: Re: [HACKERS] PostgreSQL v6.4 BETA2 ...
Следующее
От: Terry Mackintosh
Дата:
Сообщение: Re: [HACKERS] What about LIMIT in SELECT ?