Re: anti-join chosen even when slower than old plan
| От | Bruce Momjian |
|---|---|
| Тема | Re: anti-join chosen even when slower than old plan |
| Дата | |
| Msg-id | 201101270140.p0R1eoH20105@momjian.us обсуждение исходный текст |
| Ответ на | Re: anti-join chosen even when slower than old plan (Robert Haas <robertmhaas@gmail.com>) |
| Список | pgsql-performance |
Robert Haas wrote: > On Thu, Jan 20, 2011 at 4:17 AM, C?dric Villemain > <cedric.villemain.debian@gmail.com> wrote: > >>> I think his point is that we already have a proven formula > >>> (Mackert-Lohmann) and shouldn't be inventing a new one out of thin air. > >>> The problem is to figure out what numbers to apply the M-L formula to. > >>> > >>> I've been thinking that we ought to try to use it in the context of the > >>> query as a whole rather than for individual table scans; the current > >>> usage already has some of that flavor but we haven't taken it to the > >>> logical conclusion. > >> > >> Is there a TODO here? > > > > it looks like, yes. > > "Modify the planner to better estimate caching effects"? Added to TODO. -- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. +
В списке pgsql-performance по дате отправления: