lib/conceptql/nodes/complement.rb in conceptql-0.0.3 vs lib/conceptql/nodes/complement.rb in conceptql-0.0.4

@@ -4,13 +4,32 @@
   module Nodes
     class Complement < PassThru
       def query(db)
         child = children.first
         child.types.map do |type|
-          select_it(db.from(make_table_name(type)).exclude(type_id(type) => child.evaluate(db).select(type_id(type)).from_self.exclude(type_id(type) => nil)), [type])
+          positive_query = db.from(child.evaluate(db))
+            .select(:criterion_id)
+            .exclude(:criterion_id => nil)
+            .where(:criterion_type => type.to_s)
+          query = db.from(make_table_name(type))
+            .exclude(type_id(type) => positive_query)
+          db.from(select_it(query, type))
         end.inject do |union_query, q|
           union_query.union(q, all: true)
         end
       end
+
+=begin
+This is an alternate, but equally accurate way to do complement.
+We'll need to benchmark which is faster.
+      def query2(db)
+        child = children.first
+        froms = child.types.map do |type|
+          select_it(db.from(make_table_name(type)), type)
+        end
+        big_from = froms.inject { |union_query, q| union_query.union(q, all:true) }
+        db.from(big_from).except(child.evaluate(db))
+      end
+=end
     end
   end
 end