Re: Strange limit and offset behaviour....

Поиск
Список
Период
Сортировка
От Adam Rich
Тема Re: Strange limit and offset behaviour....
Дата
Msg-id 0cbf01c9896e$005ecaf0$011c60d0$@r@sbcglobal.net
обсуждение исходный текст
Ответ на Strange limit and offset behaviour....  (Bjørn T Johansen <btj@havleik.no>)
Ответы Re: Strange limit and offset behaviour....  (Bjørn T Johansen <btj@havleik.no>)
Список pgsql-general
>
> I have the following sql:
>
> SELECT * from table order by dato asc limit 20 offset 0
>
>
> This gives me different rows than the 20 first rows when running the
> following sql:
>
> SELECT * from table order by dato asc
>
>
> Shouldn't the 20 first rows in the second sql statment be the same 20
> rows that is returned in the first statement
> or am I missing something?
>

Not necessarily.  In your example query, if "dato" was not a unique
column, and there were some duplicates, the "top 20" values is not
a defined set.  Adding the offset clause might cause a different
query plan, resulting in a different ordering of the duplicate values.






В списке pgsql-general по дате отправления:

Предыдущее
От: Bjørn T Johansen
Дата:
Сообщение: Strange limit and offset behaviour....
Следующее
От: Bjørn T Johansen
Дата:
Сообщение: Re: Strange limit and offset behaviour....