[Xapian-discuss] Finding Max Possible Weight of a Document

[Olly Betts]

On Fri, Jan 26, 2007 at 06:57:37AM -0600, Kenneth Loafman wrote:
> Is there a way, without running a match, to find the max possible weight 
> of a document?  This could be with or without consideration of the 
> length of the document.  I have looked at all of the docs available on 
> the web and installed on the system and may just be overlooking it.

Are you trying to find the max possible weight of a particular document,
or of any document in the database?

If it's any document in the database, you can call Enquire::get_mset()
with maxitems = 0 and get_max_possible() on the resulting MSet will give
you an upper bound (in this case, no actual matching happens).

> The most direct way would be to sum the term weights times term freq of 
> each document, but it would be nice if there was a call to do just that.

The document weight isn't necessarily calculated by such a sum.

There's a weight from each term, which typically is a function of the
wdf (i.e. the frequency of the term in a particular document) but not
necessarily in the form of a product.  There's also an optional extra
term in the sum (dependent on document length).

Perhaps you could tell us what you're trying to achieve here?

Cheers,
    Olly