NAME

       LucyX::Search::Filter - Build a caching filter based on results of a Query.

SYNOPSIS

           my %category_filters;
           for my $category (qw( sweet sour salty bitter )) {
               my $cat_query = Lucy::Search::TermQuery->new(
                   field => 'category',
                   term  => $category,
               );
               $category_filters{$category} = LucyX::Search::Filter->new(
                   query => $cat_query,
               );
           }

           while ( my $cgi = CGI::Fast->new ) {
               my $user_query = $cgi->param('q');
               my $filter     = $category_filters{ $cgi->param('category') };
               my $and_query  = Lucy::Search::ANDQuery->new;
               $and_query->add_child($user_query);
               $and_query->add_child($filter);
               my $hits = $searcher->hits( query => $and_query );
               ...

DESCRIPTION

       A Filter is a Lucy::Search::Query subclass that can be used to filter the results of
       another Query.  The effect is very similar to simply using the wrapped inner query, but
       there are two important differences:

       •   A Filter does not contribute to the score of the documents it matches.

       •   A Filter caches its results, so it is more efficient if you use it more than once.

       To obtain logically equivalent results to the Filter but avoid the caching, substitute the
       wrapped query but use set_boost() to set its "boost" to 0.

METHODS

   new
           my $filter = LucyX::Search::Filter->new(
               query => $query;
           );

       Constructor.  Takes one hash-style parameter, "query", which must be an object belonging
       to a subclass of Lucy::Search::Query.

BUGS

       Filters do not cache when used in a search cluster with LucyX::Remote's SearchServer and
       SearchClient.