Reject blank order_values within #columns_for_distinct, as the orders aren't used at all on non-postgres adapters.

2 files changed, 3 insertions, 3 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
index 8feee23df0..a651b6c32e 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
@@ -470,7 +470,7 @@ module ActiveRecord
         # PostgreSQL requires the ORDER BY columns in the select list for distinct queries, and
         # requires that the ORDER BY include the distinct column.
         def columns_for_distinct(columns, orders) #:nodoc:
-          order_columns = orders.map{ |s|
+          order_columns = orders.reject(&:blank?).map{ |s|
               # Convert Arel node to string
               s = s.to_sql unless s.is_a?(String)
               # Remove any ASC/DESC modifiers
diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb
index ff825e52c1..a51db614cd 100644
--- a/activerecord/lib/active_record/relation/finder_methods.rb
+++ b/activerecord/lib/active_record/relation/finder_methods.rb
@@ -244,8 +244,8 @@ module ActiveRecord
     end
 
     def construct_limited_ids_condition(relation)
-      orders = relation.order_values.map { |val| val.presence }.compact
-      values = @klass.connection.columns_for_distinct("#{quoted_table_name}.#{quoted_primary_key}", orders)
+      values = @klass.connection.columns_for_distinct(
+        "#{quoted_table_name}.#{quoted_primary_key}", relation.order_values)
 
       relation = relation.dup.select(values).distinct!