Don't store defaults in the schema cache

2 files changed, 4 insertions, 5 deletions

diff --git a/activerecord/lib/active_record/attribute_methods/primary_key.rb b/activerecord/lib/active_record/attribute_methods/primary_key.rb
index e3c7344f59..f575b26d04 100644
--- a/activerecord/lib/active_record/attribute_methods/primary_key.rb
+++ b/activerecord/lib/active_record/attribute_methods/primary_key.rb
@@ -72,8 +72,8 @@ module ActiveRecord
           when :table_name_with_underscore
             base_name.foreign_key
           else
-            if ActiveRecord::Base != self && connection.schema_cache.table_exists?(table_name)
-              connection.primary_key(table_name)
+            if ActiveRecord::Base != self && table_name
+              connection.schema_cache.primary_keys[table_name]
             else
               'id'
             end
diff --git a/activerecord/lib/active_record/connection_adapters/schema_cache.rb b/activerecord/lib/active_record/connection_adapters/schema_cache.rb
index a8f7fd3648..da507fd3ae 100644
--- a/activerecord/lib/active_record/connection_adapters/schema_cache.rb
+++ b/activerecord/lib/active_record/connection_adapters/schema_cache.rb
@@ -8,7 +8,7 @@ module ActiveRecord
         @connection = conn
         @tables     = {}
 
-        @columns     = Hash.new do |h, table_name|
+        @columns = Hash.new do |h, table_name|
           h[table_name] = conn.columns(table_name, "#{table_name} Columns")
         end
 
@@ -19,8 +19,7 @@ module ActiveRecord
         end
 
         @primary_keys = Hash.new do |h, table_name|
-          h[table_name] = table_exists?(table_name) ?
-                          conn.primary_key(table_name) : 'id'
+          h[table_name] = table_exists?(table_name) ? conn.primary_key(table_name) : nil
         end
       end