[Xapian-discuss] Faster Exact Phrases

[Olly Betts]

It struck me that a lot of the complication in the handling of phrases
is because we allow the terms to occur with gaps between them.  However
in a lot of cases (probably the majority even), this generality isn't
actually used, and the window size is equal to the number of terms.

So I think it's worth considering a special case for handling such
"exact" phrases as the much simpler code path is likely to speed up
some cases.  I'm hoping it might also serve as a basis for a better
implementation of the general case.

Here's a patch (which I think should apply cleanly to 0.9.9):

http://oligarchy.co.uk/xapian/patches/faster-exact-phrases.patch

If you try it out, let us know how it does.

Cheers,
    Olly