Re: Performance
| От | Robert Haas |
|---|---|
| Тема | Re: Performance |
| Дата | |
| Msg-id | 11589CE9-B860-4024-BCDF-88FBE00FB9BC@gmail.com обсуждение исходный текст |
| Ответ на | Re: Performance (Tomas Vondra <tv@fuzzy.cz>) |
| Ответы |
Re: Performance
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| Список | pgsql-performance |
On Apr 13, 2011, at 6:19 PM, Tomas Vondra <tv@fuzzy.cz> wrote: > Yes, I've had some lectures on non-linear programming so I'm aware that > this won't work if the cost function has multiple extremes (walleys / > hills etc.) but I somehow suppose that's not the case of cost estimates. I think that supposition might turn out to be incorrect, though. Probably what will happen on simple queries is that a smallchange will make no difference, and a large enough change will cause a plan change. On complex queries it will approachcontinuous variation but why shouldn't there be local minima? ...Robert
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