Re: BUG #6327: Prefix full-text-search fails for hosts with complicated names

On Mon, 5 Dec 2011, Tom Lane wrote:

> Marcin(dot)Kasperski(at)mekk(dot)waw(dot)pl writes:
>> Synopsis
>> =========
>
>> 'goog:*' matches google.com
>> but
>> 'e-goog:*' does not match e-google.com
>
> The reason for this seems to be that the pattern is treated as a
> hyphenated word:
>
> regression=# select TO_TSQUERY('english', 'e-goog:*');
> to_tsquery
> -------------------------------
> 'e-goog':* & 'e':* & 'goog':*
> (1 row)
>
> but the hostname isn't:
>
> regression=# select TO_TSVECTOR('english', 'See e-google.com');
> to_tsvector
> --------------------------
> 'e-google.com':2 'see':1
> (1 row)
>
> If you change the text so it's not recognized as a hostname, you get
> lexemes that would match the query:
>
> regression=# select TO_TSVECTOR('english', 'See e-google com');
> to_tsvector
> ---------------------------------------------
> 'com':5 'e':3 'e-googl':2 'googl':4 'see':1
> (1 row)
>
> Possibly we could fix this by hacking the ts parser so that it would
> also apply the hyphenated-word rules to a hostname containing a dash.
>
> In general though, there are always going to be cases where prefix
> match doesn't work because of dictionary transformations ...

I'd index 'after dictionary transformations' lexemes as well as an
original to let prefix march always work.

>
> regards, tom lane
>

Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
Sternberg Astronomical Institute, Moscow University, Russia
Internet: oleg(at)sai(dot)msu(dot)su, http://www.sai.msu.su/~megera/
phone: +007(495)939-16-83, +007(495)939-23-83