Re: anti-join chosen even when slower than old plan
От | Robert Haas |
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Тема | Re: anti-join chosen even when slower than old plan |
Дата | |
Msg-id | AANLkTi=OYC2dN1SkaSY5AEyOVd4Zu-YPTgW-YKV=+xsj@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: anti-join chosen even when slower than old plan (Cédric Villemain <cedric.villemain.debian@gmail.com>) |
Ответы |
Re: anti-join chosen even when slower than old plan
Re: anti-join chosen even when slower than old plan |
Список | pgsql-performance |
On Thu, Jan 20, 2011 at 4:17 AM, Cédric 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"? -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
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