no INNER JOIN on get rank in simple cases.

lib/pg_search/scope_options.rb

@@ -14,14 +14,11 @@ def initialize(config)
 
     def apply(scope)
       scope = include_table_aliasing_for_rank(scope)
-      rank_table_alias = scope.pg_search_rank_table_alias(:include_counter)
-
-      scope
-        .joins(rank_join(rank_table_alias))
-        .order("#{rank_table_alias}.rank DESC, #{order_within_rank}")
-        .extend(DisableEagerLoading)
-        .extend(WithPgSearchRank)
-        .extend(WithPgSearchHighlight[feature_for(:tsearch)])
+      if config.associations.any?
+        apply_with_inner_join(scope)
+      else
+        apply_without_inner_join(scope)
+      end
     end
 
     # workaround for https://github.com/Casecommons/pg_search/issues/14
@@ -63,6 +60,39 @@ def with_pg_search_rank
         scope = scope.select("#{table_name}.*") unless scope.select_values.any?
         scope.select("#{pg_search_rank_table_alias}.rank AS pg_search_rank")
       end
+
+      def where_pg_search_rank(value)
+        scope = self
+        scope.where("#{PgSearch::Configuration.alias(table_name)}.rank#{value}")
+      end
+    end
+
+    module WithPgSearchRankNoInnerJoin
+      def self.[](rank_value)
+        Module.new do
+          include WithPgSearchRankNoInnerJoin
+          define_method(:rank_value) { rank_value }
+        end
+      end
+
+      def rank_field
+        "#{rank_value} AS pg_search_rank"
+      end
+
+      def rank_value
+        raise TypeError.new("You need to instantiate this module with []")
+      end
+
+      def with_pg_search_rank
+        scope = self
+        scope = scope.select("#{table_name}.*") unless scope.select_values.any?
+        scope.select(rank_field)
+      end
+
+      def where_pg_search_rank(value)
+        scope = self
+        scope.where("#{rank_value}#{value}")
+      end
     end
 
     module PgSearchRankTableAliasing
@@ -94,6 +124,26 @@ def pg_search_scope_application_count_plus_plus
 
     delegate :connection, :quoted_table_name, :to => :model
 
+    def apply_with_inner_join(scope)
+      rank_table_alias = scope.pg_search_rank_table_alias(:include_counter)
+
+      scope
+        .joins(rank_join(rank_table_alias))
+        .order("#{rank_table_alias}.rank DESC, #{order_within_rank}")
+        .extend(DisableEagerLoading)
+        .extend(WithPgSearchRank)
+        .extend(WithPgSearchHighlight[feature_for(:tsearch)])
+    end
+
+    def apply_without_inner_join(scope)
+      scope
+        .where(conditions)
+        .order("#{rank_order}, #{order_within_rank}")
+        .extend(DisableEagerLoading)
+        .extend(WithPgSearchRankNoInnerJoin[rank])
+        .extend(WithPgSearchHighlight[feature_for(:tsearch)])
+    end
+
     def subquery
       model
         .unscoped
@@ -170,6 +220,10 @@ def rank_join(rank_table_alias)
       "INNER JOIN (#{subquery.to_sql}) AS #{rank_table_alias} ON #{primary_key} = #{rank_table_alias}.pg_search_id"
     end
 
+    def rank_order
+      "#{rank} DESC"
+    end
+
     def include_table_aliasing_for_rank(scope)
       if scope.included_modules.include?(PgSearchRankTableAliasing)
         scope

spec/integration/pg_search_spec.rb

@@ -344,7 +344,7 @@
         twice = ModelWithPgSearch.create!(:content => 'foo foo')
 
         records = ModelWithPgSearch.search_content('foo')
-                  .where("#{PgSearch::Configuration.alias(ModelWithPgSearch.table_name)}.rank > 0.07")
+                      .where_pg_search_rank(' > 0.07')
 
         expect(records).to eq [twice]
       end