[Xapian-discuss] Omega

[Olly Betts]

On Wed, Feb 08, 2006 at 08:46:44AM -0500, Jim Lynch wrote:
> Thanks, now I want to extend omega to include variable proximity 
> searches and added the following at the beginning of the run_query function:
>        vector<string> myTerms;
>        myTerms.push_back("less");
>        myTerms.push_back("february");

If you're stemming at index time, then february -> februari here.

On Wed, Feb 08, 2006 at 11:14:29AM -0500, Jim Lynch wrote:
> I don't know if I figured out my problem or a way around it, but I've 
> got something that works sort of.    Instead of using strings, I 
> generated Xapian::Query objects and put them in the vector.  I used the 
> query_parser method to generate the objects.

And the QueryParser stems by default which is why this approach works.

> My next question is what is the significance of the "pos" parameters in 
> the following output from get_description()
> 
> Xapian::Query(((toward:(pos=1) NEAR 11 posit:(pos=2)) OR less:(pos=3)))
> 
> When I do it programmatically I get pos=1 for all.  That didn't seem to 
> make a difference in the results however I'd like to know what it means.

I think it's only used to list terms in "original query order" when you
ask for the terms matching a document.  The query 'hello +world' becomes
'world AND_MAYBE hello', so the order isn't always preserved.

You can set it using the Query(TERM, WQF, POS) constructor:

http://www.xapian.org/docs/apidoc/html/classXapian_1_1Query.html#a4

Cheers,
    Olly