Re: Fragments in tsearch2 headline

On 30/10/2007, Richard Huxton <dev@archonet.com> wrote:
> Oleg Bartunov wrote:
> > Catalin,
> >
> > what is your need ? What's wrong with this ?
> >
> > postgres=# select ts_headline('1 2 3 4 5 3 4 abc abc 2 3
> > xyz','2'::tsquery, 'StartSel=...,StopSel=...')
> > ;
> >                 ts_headline
> > -------------------------------------------
> >  1 ...2... 3 4 5 3 4 abc abc ...2... 3 xyz
>
> I think he want's something like: "1 2 3 ... abc 2 3 ..."
>
> A few characters of context around each match and then ... between. Kind
> of like grep -C.

That's pretty much correct (with the difference that I'd like context
of words rather than lines as in "grep" and StartSel=<b>,
StopSel=</b>).

Since the text I want a headline for might be pretty long (tens of
lines), I'd like to only show the excerpts around the matching words.
Similar to the above example:

select ts_headline('1 2 3 4 5 3 4 abc x y z 2 3', '2 & abc'::tsquery);

should give:

'1 <b>2</b> 3 4 ... 3 4 <b>abc</b> x y'

Currently, if you limit the maximum words so that 'abc' is too far, it
only highlights the first match.

Many of the search engines (including google) show the headline this
way. I think Lucene can do this as well but I've never used it to be
sure.

--
Catalin