Re: [Proposal] Global temporary tables
От | Tomas Vondra |
---|---|
Тема | Re: [Proposal] Global temporary tables |
Дата | |
Msg-id | 20200113210301.yakqxdmxjh2ogq6x@development обсуждение исходный текст |
Ответ на | Re: [Proposal] Global temporary tables (Julien Rouhaud <rjuju123@gmail.com>) |
Список | pgsql-hackers |
On Mon, Jan 13, 2020 at 09:12:38PM +0100, Julien Rouhaud wrote: >On Mon, Jan 13, 2020 at 05:32:53PM +0100, Tomas Vondra wrote: >> On Mon, Jan 13, 2020 at 11:08:40AM +0300, Konstantin Knizhnik wrote: >> > >> >"if any code tried to access the statistics directly from the table, >> >rather than via the caches". >> > >> >Currently optimizer is accessing statistic though caches. So this >> >approach works. If somebody will rewrite optimizer or provide own >> >custom optimizer in extension which access statistic directly >> >then it we really be a problem. But I wonder why bypassing catalog >> >cache may be needed. >> > >> >> I don't know, but it seems extensions like hypopg do it. > >AFAIR, hypopg only opens pg_statistic to use its tupledesc when creating >statistics on hypothetical partitions, but it should otherwise never reads or >need plain pg_statistic rows. Ah, OK! Thanks for the clarification. I knew it does something with the catalog, didn't realize it only gets the descriptor. regards -- Tomas Vondra http://www.2ndQuadrant.com PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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