Scoring in riak-search

Ryan Zezeski rzezeski at basho.com
Mon Oct 15 12:37:28 EDT 2012


Niklas,

On Wed, Oct 10, 2012 at 9:44 AM, Niklas Saers <njs at trifork.com> wrote:
>
>
> When I do a search, I receive a responseHeader that has a maxScore. That's
> great, but the score for the individual documents doesn't show. How do I
> get the score for the individual documents listed in my search? I want to
> use this to display to my users 1-5 stars of how well they matched.
>

This is a bug in the Solr-like interface to Riak Search.  It discards the
score when building the response.


>
> Secondly, if I add a postfix * to any of my search terms, it searches
> fine, but maxScore says 0.00000e+0. Why is this?
>

This is because a single prefix query, e.g. motor*, will use a range op.  A
range op doesn't affect scoring [1].  Since no non-suffix query was given
along with it there is no scoring information and it defaults to 0.


>
> And finally, if I add a weight after my postfix *, i.e. ^5, I get "Unable
> to parse request: {badmatch, {error, { lucene_parse, "syntax error before:
> 5.0" } } }  Why is this? As far as I can understand from the docs, a query
> such as "title:listening*^5" should be fine?
>

The parser doesn't understand this query.  Even if it did it wouldn't
matter because the range op doesn't respect boosting.

For the last few months I've been working on a new search solution for Riak
that uses Solr directly [2].  That is, unlike Riak Search which pretends to
look like Solr it actually is Solr underneath.  Queries like the above,
plus many more, are supported.  I know that doesn't help your current
situation but if you want to learn more feel free to contact me on a
backchannel.

-Z

[1]:
https://github.com/basho/riak_search/blob/1.2.1/src/riak_search_op_range_sized.erl#L20


[2]: https://github.com/rzezeski/yokozuna
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.basho.com/pipermail/riak-users_lists.basho.com/attachments/20121015/fd77dc6d/attachment.html>


More information about the riak-users mailing list