Remove `Column#primary`

It appears to have been used at some point in the past, but is no longer
used in any meaningful way. Whether a column is considered primary is
a property of the model, not the schema/column. This also removes the
need for yet another layer of caching of the model's schema, and we can
leave that to the schema cache.

3 files changed, 5 insertions, 12 deletions

diff --git a/activerecord/lib/active_record/attribute_methods.rb b/activerecord/lib/active_record/attribute_methods.rb
index 8bd51dc71f..d44aebec39 100644
--- a/activerecord/lib/active_record/attribute_methods.rb
+++ b/activerecord/lib/active_record/attribute_methods.rb
@@ -455,7 +455,7 @@ module ActiveRecord
     end
 
     def pk_attribute?(name)
-      column_for_attribute(name).primary
+      name == self.class.primary_key
     end
 
     def typecasted_attribute_value(name)
diff --git a/activerecord/lib/active_record/connection_adapters/column.rb b/activerecord/lib/active_record/connection_adapters/column.rb
index 704868c058..42aabd6d7f 100644
--- a/activerecord/lib/active_record/connection_adapters/column.rb
+++ b/activerecord/lib/active_record/connection_adapters/column.rb
@@ -14,7 +14,7 @@ module ActiveRecord
       end
 
       attr_reader :name, :default, :cast_type, :null, :sql_type, :default_function
-      attr_accessor :primary, :coder
+      attr_accessor :coder
 
       alias :encoded? :coder
 
@@ -36,7 +36,6 @@ module ActiveRecord
         @null             = null
         @default          = extract_default(default)
         @default_function = nil
-        @primary          = nil
         @coder            = nil
       end
 
diff --git a/activerecord/lib/active_record/model_schema.rb b/activerecord/lib/active_record/model_schema.rb
index aa1166750f..8449fb1266 100644
--- a/activerecord/lib/active_record/model_schema.rb
+++ b/activerecord/lib/active_record/model_schema.rb
@@ -219,16 +219,12 @@ module ActiveRecord
 
       # Returns an array of column objects for the table associated with this class.
       def columns
-        @columns ||= connection.schema_cache.columns(table_name).map do |col|
-          col = col.dup
-          col.primary = (col.name == primary_key)
-          col
-        end
+        connection.schema_cache.columns(table_name)
       end
 
       # Returns a hash of column objects for the table associated with this class.
       def columns_hash
-        @columns_hash ||= Hash[columns.map { |c| [c.name, c] }]
+        connection.schema_cache.columns_hash(table_name)
       end
 
       def column_types # :nodoc:
@@ -271,7 +267,7 @@ module ActiveRecord
       # Returns an array of column objects where the primary id, all columns ending in "_id" or "_count",
       # and columns used for single table inheritance have been removed.
       def content_columns
-        @content_columns ||= columns.reject { |c| c.primary || c.name =~ /(_id|_count)$/ || c.name == inheritance_column }
+        @content_columns ||= columns.reject { |c| c.name == primary_key || c.name =~ /(_id|_count)$/ || c.name == inheritance_column }
       end
 
       # Resets all the cached information about columns, which will cause them
@@ -308,8 +304,6 @@ module ActiveRecord
         @arel_engine             = nil
         @column_defaults         = nil
         @column_names            = nil
-        @columns                 = nil
-        @columns_hash            = nil
         @column_types            = nil
         @content_columns         = nil
         @dynamic_methods_hash    = nil