Re: gnus-search-imap and quoted queries

[Eric Abrahamsen <eric@ericabrahamsen.net>]

Sergio Durigan Junior <sergiodj@sergiodj.net> writes:

> On Saturday, April 23 2022, Eric Abrahamsen wrote:
>
>> Sergio Durigan Junior <sergiodj@sergiodj.net> writes:
>>
>>> On Tuesday, April 19 2022, I wrote:
>>>
>>>> I have GNUS configured to use a local Dovecot IMAP server (a fairly
>>>> common setup, I think) and I've been trying to get gnus-search-imap
>>>> working.  I set gnus-search-use-parsed-queries to t, by the way.
>>>>
>>>> I noticed that when I specify a quoted query as the search input, the
>>>> results don't reflect what I'd expect.
>>>
>>> FWIW, I finally had some time to look deeper into this and found that
>>> the culprit was the Dovecot FTS plugin I was using (fts-xapian).
>>> It doesn't follow the IMAP RFC strictly and therefore can't/won't do
>>> substring searches.
>>>
>>> I'm now using another Xapian-based plugin called fts-flatcurve which
>>> DTRT.
>>>
>>> Thanks for the help, it's been fun investigating this problem.
>>
>> Hey that's pretty interesting. Looks like I'm using lucene, which seems
>> to work fine. I wonder if it merits a brief mention in the manual that
>> different backends behave differently.
>
> I certainly wouldn't mind seeing this possible idiosyncrasy mentioned in
> the manual.  WDYT about the patch below?
>
> -- 
> Sergio
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>
> From ff85d8b3df751342de6b0071b9c17688086fe744 Mon Sep 17 00:00:00 2001
> From: Sergio Durigan Junior <sergiodj@sergiodj.net>
> Date: Sun, 1 May 2022 01:11:42 -0400
> Subject: [PATCH] Mention different behaviours in IMAP FTS plugins
>
> * doc/misc/gnus.texi (Search Engines): Mention different behaviours in
> IMAP FTS plugins.
> ---
>  doc/misc/gnus.texi | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/doc/misc/gnus.texi b/doc/misc/gnus.texi
> index e51ae7d424d..03330224e09 100644
> --- a/doc/misc/gnus.texi
> +++ b/doc/misc/gnus.texi
> @@ -21727,6 +21727,13 @@ Search Engines
>  to manage updates yourself, though this will likely change in the
>  future.
>  
> +If you use the IMAP search engine you may want to configure your IMAP
> +server to provide Full Text Search (FTS) functionality, which greatly
> +improves the performance and results.  Beware though that some FTS
> +backends may not implement text search as described by RFC 3501, which
> +states that substring search should be performed.  This difference in
> +behaviour can ultimately affect the search results.
> +
>  Lastly, all search engines accept a @code{raw-queries-p} option.  This
>  indicates that engines of this type (or this particular engine) should
>  always use raw queries, never parsed (@pxref{Search Queries}).

Looks good to me! Thanks.