When using a percolator "metadata query", the desired behavior is almost always to use the query for sorting. But the user needs to know that track_scores also needs to be toggled.

It would be more user-friendly if using a query implicitly toggled track_scores. The option should still remain if the user doesn't actually want it, but the default should switch to make it more convenient to use.

So instead of this:

curl -XGET 'localhost:9200/news/item/_percolate' -d '{
    "doc" : {
        ...
    },
    "query" : {
        ...
    },
    "track_scores" : true
}'

A user would just specify the query:

curl -XGET 'localhost:9200/news/item/_percolate' -d '{
    "doc" : {
        ...
    },
    "query" : {
        ...
    }
}'

And scores are tracked implicitly unless changed.