[Xapian-discuss] Faster "sort by value"

[Olly Betts]

Thanks for testing, Arjen.

On Thu, Jun 08, 2006 at 08:03:28PM +0200, Arjen van der Meijden wrote:
> Running only those two 'no sort'-variants shows they don't really differ 
> in accumulated times. Perhaps the old-sorting-code pushes a bit of data 
> out of memory?

Yes, it'll read a lot of the record B-tree (which holds the document
data - i.e. what you get from get_data()) which will tend to push
more useful information out of the disk cache.  So this tweak will
also help non-sort-by-value searches in a system which uses
sort-by-value.

> So there is a nice improvement with a factor varying from 3 to 9 orso.

That's not bad.

> But the value-sorting still takes about a factor 8-10 more than the 
> relevance-sorted, so there might be a bit more room for improvement?

I think there is, but I doubt it'll be as easy as this was to achieve.
I suspect sort-by-value is inevitably going to be a bit slower.

Anyway, I'll commit this shortly.

Cheers,
    Olly