Re: estimating # of distinct values

Поиск
Список
Период
Сортировка
От Tom Lane
Тема Re: estimating # of distinct values
Дата
Msg-id 25249.1295466403@sss.pgh.pa.us
обсуждение исходный текст
Ответ на Re: estimating # of distinct values  (Robert Haas <robertmhaas@gmail.com>)
Ответы Re: estimating # of distinct values  (Tomas Vondra <tv@fuzzy.cz>)
Список pgsql-hackers
Robert Haas <robertmhaas@gmail.com> writes:
> ... I guess I'm just saying I'd think really, really hard
> before abandoning the idea of periodic sampling.  You have to get an
> awful lot of benefit out of those cross-column stats to make it worth
> paying a run-time cost for them.

I've been trying to not discourage Tomas from blue-sky speculation,
but I have to say I agree with Robert that the chance of any usable
result from this approach is very very small.  Feel free to do some
experimentation to prove us wrong --- but don't put a lot of effort
into it before that.
        regards, tom lane


В списке pgsql-hackers по дате отправления:

Предыдущее
От: Robert Haas
Дата:
Сообщение: Re: ToDo List Item - System Table Index Clustering
Следующее
От: Tom Lane
Дата:
Сообщение: Re: Re: patch: fix performance problems with repated decomprimation of varlena values in plpgsql