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

Heikki Linnakangas <[email protected]> Fri, 05 Sep 2008 20:25:56 +0300
Newsgroups gmane.comp.db.postgresql.devel.patches
Organization EnterpriseDB
Message-ID <[email protected]>
Tom Lane wrote:
> "David Rowley" <[email protected]> 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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