Re: Index creation takes for ever

Поиск
Список
Период
Сортировка
От Zeugswetter Andreas SB SD
Тема Re: Index creation takes for ever
Дата
Msg-id 46C15C39FEB2C44BA555E356FBCD6FA4961FFD@m0114.s-mxs.net
обсуждение исходный текст
Ответ на Index creation takes for ever  (ohp@pyrenet.fr)
Ответы Re: Index creation takes for ever  (Manfred Koizar <mkoi-pg@aon.at>)
Список pgsql-hackers
> > I don't think so, because the patch does nothing to keep the sort
> > order once the index is initially created.
>
> As Tom mentioned, we might not want to keep the tid's in order after the
> index is created because he wants the most recent tid's first, so the
> expired ones migrate to the end.

But on average this argument only holds true for unique indexes, no ?
Is there any code that stops the heap lookup after the visible tuple is found ?
At least in an index with more rows per key you will fetch all heaps after the
first one anyway to get at the next row. This is better done in heap order, no ?

And the bitmap approach will not work for large result sets.

Summa summarum I would leave the TODO item (maybe add a comment
(only for non-unique, evaluate performance))

Andreas

В списке pgsql-hackers по дате отправления:

Предыдущее
От: Mark Kirkwood
Дата:
Сообщение: dump cache summary
Следующее
От: "Gaetano Mendola"
Дата:
Сообщение: Re: mcxt.c