Re: [HACKERS] bushy plans
От | Bruce Momjian |
---|---|
Тема | Re: [HACKERS] bushy plans |
Дата | |
Msg-id | 199902150531.AAA29547@candle.pha.pa.us обсуждение исходный текст |
Ответ на | Re: [HACKERS] bushy plans (Vadim Mikheev <vadim@krs.ru>) |
Список | pgsql-hackers |
> > Please tell me what they are supposed to do. I can get it working, I > > think. I will not remove it. I have ifdef'ed it, though. If you tell > > me what it is, I will check it to see if it works. > > It doesn't work (failed assertion). > > Well, currently both geqo and old optimizer produces > left-sided plans: inner relation of an join is always > _base_ relation (not join relation). In bushy plans > both outer and inner relations may be join ones. > ~1.5 - 2 years ago I added right-sided plans: > outer relation is base, inner relation may be join. > Sometimes right-sided plans are 30% faster than left-sided. > Bushy plans could be more faster... > BTW, I broke execution of right-sided plans ~ 1 year ago > while implementing subqueries (near materialization node) > and still have no time to fix it (seems no one except me > used them so I didn't worry about this -:)). This explaination helps greatly. This clears up what is happening in the code. I will keep the bushy stuff, and see if I can get it working, though if the problem is outside of the optimizer, I will have trouble. -- Bruce Momjian | http://www.op.net/~candle maillist@candle.pha.pa.us | (610) 853-3000+ If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania19026
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