Fetch Function Parameter: boost_functions

Boosts can be passed as function boosts which should be done according to the Solr function query syntax.

The fetch parameter should be specified as:

{set $search=fetch( ezfind,search,
        hash( 'query', $search_text,
        ... ,
        'boost_functions', hash('functions',
array('<boostfunction n>', ...)),
        ...

where 'boost function n' should adhere to technical syntax of Solr functions.

Note: The Solr query syntax is quite elaborate but powerful, and documented on the Solr wiki pages: http://wiki.apache.org/solr/FunctionQuery

For example, the following boost function will favor more recent pages over older ones:

{set $search=fetch( ezfind,
       hash( 'query', $search_text,
            'offset', $view_parameters.offset,
            'limit', $page_limit,
            'sort_by', hash( 'score', 'desc' ),
            'boost_functions', hash('functions',
array('recip(ms(NOW/HOUR,meta_published_dt),4e-12,1000,2)')) )}