Re: [HACKERS] TODO item: Implement Boyer-Moore searching (First time hacker)

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От Heikki Linnakangas
Тема Re: [HACKERS] TODO item: Implement Boyer-Moore searching (First time hacker)
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Msg-id 48C16BA4.2060407@enterprisedb.com
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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)  (Tom Lane <tgl@sss.pgh.pa.us>)
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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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