Cross-platform DISTINCT that doesn't work without surprises is a lost cause.

Implement this against the result if you desire.

lib/ransack/adapters/active_record/3.0/context.rb

@@ -13,8 +13,7 @@ module Ransack
 
         def evaluate(search, opts = {})
           viz = Visitor.new
-          relation = @object.where(viz.accept(search.base)).order(viz.accept(search.sorts))
-          opts[:distinct] ? relation.select("DISTINCT #{@klass.quoted_table_name}.*") : relation
+          @object.where(viz.accept(search.base)).order(viz.accept(search.sorts))
         end
 
         def attribute_method?(str, klass = @klass)

lib/ransack/adapters/active_record/context.rb

@@ -11,8 +11,7 @@ module Ransack
 
         def evaluate(search, opts = {})
           viz = Visitor.new
-          relation = @object.where(viz.accept(search.base)).order(viz.accept(search.sorts))
-          opts[:distinct] ? relation.select("DISTINCT #{@klass.quoted_table_name}.*") : relation
+          @object.where(viz.accept(search.base)).order(viz.accept(search.sorts))
         end
 
         def attribute_method?(str, klass = @klass)

spec/ransack/search_spec.rb

@@ -129,12 +129,6 @@ module Ransack
         where.to_sql.should match /\("people"."name" = 'Ernie' OR "children_people"."name" = 'Ernie'\) AND \("people"."name" = 'Bert' OR "children_people"."name" = 'Bert'\)/
       end
 
-      it 'returns distinct records when passed :distinct => true' do
-        search = Search.new(Person, :g => [{:m => 'or', :comments_body_cont => 'e', :articles_comments_body_cont => 'e'}])
-        search.result.should have(920).items
-        search.result(:distinct => true).should have(330).items
-        search.result.all.uniq.should eq search.result(:distinct => true).all
-      end
     end
 
     describe '#sorts=' do