Re: Improving N-Distinct estimation by ANALYZE
От | Simon Riggs |
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Тема | Re: Improving N-Distinct estimation by ANALYZE |
Дата | |
Msg-id | 1136419500.21025.204.camel@localhost.localdomain обсуждение исходный текст |
Ответ на | Re: Improving N-Distinct estimation by ANALYZE (Tom Lane <tgl@sss.pgh.pa.us>) |
Список | pgsql-hackers |
On Wed, 2006-01-04 at 14:49 -0500, Tom Lane wrote: > Simon Riggs <simon@2ndquadrant.com> writes: > > [ ... a large amount of analysis based on exactly one test case ... ] [Hmmm, those are your opinions, not my words. Funny guy ;-) ] The one test case just happens to be a very common 1:M relationship, an example of which occurs within the TPC-H/DBT-3 test database. I picked that so it was an obvious publicly accessible test case, rather than an isolated customer issue that couldn't be aired fully. I was hoping to allow the problem to be explored and improved. > I think you are putting too much emphasis on fixing one case and not > enough on considering what may happen in other cases ... It's not just one problem, but knowing that you would accept only a detailed analysis, I researched that one case so that it was indisputable. > I'm dubious about the rest of this. Excellent. Much better than "It's Wrong." I'll write some code and run some tests. Thanks for reading it all; sorry it had to be so long. Best Regards, Simon Riggs
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