[Xapian-discuss] Performance of range searches

[Olly Betts]

On Fri, Oct 31, 2008 at 04:41:15PM -0700, Alex Neth wrote:
> Is there any way to improve the performance of range searches?

You didn't say which Xapian version you're using.  One of the changes in
1.0.7 improves value range performance in some cases, so make sure
you're using 1.0.7 or newer.

There are improvements to how values are stored in the development
"chert" backend in SVN trunk.  This isn't taken full advantage of by
value ranges yet, but once that's also fixed, you should find they're
lots faster than currently.

With 1.0.x there are a couple of tricks to help improve the speed (these
will be irrelevant for Xapian >= 1.1.0).  Firstly, make sure that you
aren't storing any values which you don't actually use currently (1.0.x
has to retrieve all values for a document just to get one).  And
secondly store the most speed critical values in the lower numbered
value slots (1.0.x has to unpack the values for a given document
linearly to get the one it wants).

Cheers,
    Olly