[Xapian-discuss] Xapian 1.0.18 released

[Olly Betts]

On Thu, Mar 11, 2010 at 06:24:00PM +0100, Jesper Krogh wrote:
> Olly Betts wrote:
> > I've uploaded Xapian 1.0.18 [...]
> > 
> > Flint backend:
> > 
> > * When updating documents, don't update posting entries which haven't changed
> >   (ticket#250). 
> 
> In my application a prepare a "new" document, search the index for and
> existing one and call replace_document with the new document if it
> should be replaced. If the documents does not differ much, will the
> optimization apply in this case? Or is it only when doing modifications
> to existing documents?

It works for your case too, but for flint the document length is stored with
every posting entry, so if the document length changes, every posting has
to be rewritten anyway.  That's equally true for modifying an existing
document.

The chert backend in 1.1.x is saner and only stores the document lengths
once in a separate structure, so it benefits more from this optimisation.

Cheers,
    Olly