Re: [HACKERS] TODO item: Implement Boyer-Moore searching (First time hacker)
От | Heikki Linnakangas |
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Тема | Re: [HACKERS] TODO item: Implement Boyer-Moore searching (First time hacker) |
Дата | |
Msg-id | 48C16BA4.2060407@enterprisedb.com обсуждение исходный текст |
Ответ на | Re: [HACKERS] TODO item: Implement Boyer-Moore searching (First time hacker) (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: [HACKERS] TODO item: Implement Boyer-Moore searching (First time hacker)
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Список | pgsql-patches |
Tom Lane wrote: > "David Rowley" <dgrowley@gmail.com> writes: >> Tom Lane wrote: >>> Hmm. B-M-H has worst case search speed O(M*N) (where M = length of >>> pattern, N = length of search string); whereas full B-M is O(N). Maybe we >>> should build the second table when M is large? > >> I'll look into this. If it pays off for longer searches I'll submit a patch. >> I won't have the time until after the 15th, so perhaps that's in November's >> commit fest? > > Yes. Let's get B-M-H in during this fest and then you can look into > whether a follow-on patch is worthwhile. Agreed. Also, it would be nice to use B-M(-H) for LIKE as well. That's a different codepath, but probably more widely used than textpos and frients. I haven't looked how feasible it would be to do, though. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com
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