Re: [HACKERS] [PATCH] Overestimated filter cost and its mitigation
От | Michael Paquier |
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Тема | Re: [HACKERS] [PATCH] Overestimated filter cost and its mitigation |
Дата | |
Msg-id | CAB7nPqQrUETd-AJqi51CVvE3LQ=zM9w-uBUga=UsYd0jmjq_kw@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: [HACKERS] [PATCH] Overestimated filter cost and its mitigation (Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>) |
Ответы |
Re: [HACKERS] [PATCH] Overestimated filter cost and its mitigation
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Список | pgsql-hackers |
On Thu, Nov 9, 2017 at 12:33 PM, Ashutosh Bapat <ashutosh.bapat@enterprisedb.com> wrote: > Looking at order_qual_clauses(), we can say that a set of quals q1 > .... qn are ordered the same irrespective of the set of clauses they > are subset of. E.g. if {q1 .. qn} is subset of Q (ordered as Qo) and > also Q' (ordered as Q'o) the order in which they appear in Qo and Q'o > is same. So, even if different paths segregate the clauses in > different set, within each set the order is same. FWIW, we can order > all clauses in largest set once and use that order every time. Albeit > we will have to remember the order somewhere OR make the separator > routine retain the order in the larger set, which I guess is true > about all separator functions. I am not sure what to think about this patch, so moved to next CF. The patch still applies. Hayamizu-san, it would be nice as well if you could review other's patches. One patch reviewed for one patch submitted, with equal difficulty. You should also get a community account so as it is possible to add your name as an author of this patch. -- Michael
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