Date: Mon, 24 Jan 2022 14:28:00 -0500
From: Bruce Momjian <bruce@momjian.us>
To: Laurenz Albe <laurenz.albe@cybertec.at>
Cc: James Addison <jay@jp-hosting.net>, pgsql-www@postgresql.org
Subject: Re: Mailing list search engine: surprising missing results?
Message-ID: <Ye79wNIXsyhwwwce@momjian.us>
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On Mon, Jan 24, 2022 at 08:27:41AM +0100, Laurenz Albe wrote:
> On Sun, 2022-01-23 at 12:49 +0000, James Addison wrote:
> > Specializing the query further and searching for
> > "boyer-moore-horspool"[4] *does* again return results -- two documents
> > -- with the terms "boyer" and "horspool" highlighted.
> 
> This is caused by the peculiarities of PostgreSQL full text search:
> 
> SELECT to_tsvector('english', 'Boyer-Moore-Horspool')
>        @@ websearch_to_tsquery('english', 'boyer-moore');
> 
>  ?column?
> ══════════
>  f
> (1 row)
> 
> The reason is that the 'moore' in 'boyer-moore' is stemmed, since it
> is at the end of the word, while the 'moore' in 'Boyer-Moore-Horspool'
> isn't:

Wow, he showed me this problem earlier but I never suspected it was
stemming issue because I never considered proper nowns could be
stem-adjusted, but it is obvious they can.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

  If only the physical world exists, free will is an illusion.