Re: Optimize join selectivity estimation by not reading MCV stats for unique join attributes

Поиск
Список
Период
Сортировка
От Richard Guo
Тема Re: Optimize join selectivity estimation by not reading MCV stats for unique join attributes
Дата
Msg-id CAMbWs4_v47mP3VCoqo=7GjL59rDnYPDokCqjHKsJ+gbeRY4bqA@mail.gmail.com
обсуждение исходный текст
Ответ на Re: Optimize join selectivity estimation by not reading MCV stats for unique join attributes  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: Optimize join selectivity estimation by not reading MCV stats for unique join attributes  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-hackers
Дерево обсуждения

On Fri, Nov 18, 2022 at 9:36 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
Actually, looking at get_attstatslot, I realize it was already designed
to do that -- just pass zero for flags.  So we could do it as attached.
 
Yes, it is.  Using zero flag would short-cut get_attstatsslot() to just
return whether the slot type exists without loading it.  Do you think we
need to emphasize this use case in the comments for 'flags'?  It seems
currently there is no such use case in the codes on HEAD.

I wonder whether we need to also check statistic_proc_security_check()
when determining if MCVs exists in both sides.

Thanks
Richard

В списке pgsql-hackers по дате отправления:

Предыдущее
От: Andres Freund
Дата:
Сообщение: Re: Strange failure on mamba
Следующее
От: Amit Kapila
Дата:
Сообщение: Re: Perform streaming logical transactions by background workers and parallel apply