[Xapian-devel] Backend for Lucene format indexes-How to get doclength

[Olly Betts]

On Mon, Sep 02, 2013 at 09:21:48AM +0800, jiangwen jiang wrote:
> TfIdfWeight and BM25(b=0) also need wdf_upper_bound, it is not exists in
> Lucene backends.

If you don't provide an implementation of wdf_upper_bound(), the default
is to use the collection frequency of the term, so provided that
information is available in the lucene files, the lack of
wdf_upper_bound information isn't a show stopper.

> I think this data will be caculated when doing copydatabase, I will update
> the code later

That's probably a good plan though.

Cheers,
    Olly