From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
---|---|
To: | marcin mank <marcin(dot)mank(at)gmail(dot)com> |
Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: bug: fuzzystrmatch levenshtein is wrong |
Date: | 2009-12-09 02:04:02 |
Message-ID: | 603c8f070912081804y16268436t3e1b12d7d2ac4bf4@mail.gmail.com |
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Lists: | pgsql-hackers |
On Mon, Dec 7, 2009 at 8:33 AM, marcin mank <marcin(dot)mank(at)gmail(dot)com> wrote:
> The current behavior of levenshtein(text,text,int,int,int) is wrong. Consider:
>
> leki_dev=# select levenshtein('','a',2,4,5);
> levenshtein
> -------------
> 1
> (1 row)
>
>
> leki_dev=# select levenshtein('a','',2,4,5);
> levenshtein
> -------------
> 1
> (1 row)
>
>
> leki_dev=# select levenshtein('aa','a',2,4,5);
> levenshtein
> -------------
> 1
> (1 row)
>
>
> leki_dev=# select levenshtein('a','aa',2,4,5);
> levenshtein
> -------------
> 1
> (1 row)
>
> versus (after patch)
>
> postgres=# select levenshtein('','a',2,4,5);
> levenshtein
> -------------
> 2
> (1 row)
>
> postgres=# select levenshtein('a','',2,4,5);
> levenshtein
> -------------
> 4
> (1 row)
>
> postgres=# select levenshtein('aa','a',2,4,5);
> levenshtein
> -------------
> 4
> (1 row)
>
> postgres=# select levenshtein('a','aa',2,4,5);
> levenshtein
> -------------
> 2
> (1 row)
>
> patch attached.
I cannot get this patch to apply for anything. All 4 hunks fail, both
on HEAD and on the the pre-8.4-pgindent version of fuzzystrmatch.c.
Either I'm doing something wrong here, or there's something wrong with
this patch file.
...Robert
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