PERF: avoid allocating column names where possible

When requesting columns names from database adapters AR:Result
would dup/freeze column names, this prefers using fstrings which
cuts down on repeat allocations

Attributes that are retained keep these fstrings around for the long
term

Note, this has the highest impact on "short" result sets, eg: Topic.first where you can void allocating the number of columns * String.

2 files changed, 2 insertions, 2 deletions

diff --git a/activerecord/lib/active_record/attribute_methods.rb b/activerecord/lib/active_record/attribute_methods.rb
index 83b5a5e698..e4b8b1a330 100644
--- a/activerecord/lib/active_record/attribute_methods.rb
+++ b/activerecord/lib/active_record/attribute_methods.rb
@@ -26,7 +26,7 @@ module ActiveRecord
       def self.set_name_cache(name, value)
         const_name = "ATTR_#{name}"
         unless const_defined? const_name
-          const_set const_name, value.dup.freeze
+          const_set const_name, -value
         end
       end
     }
diff --git a/activerecord/lib/active_record/result.rb b/activerecord/lib/active_record/result.rb
index e54e8086dd..11626c8e31 100644
--- a/activerecord/lib/active_record/result.rb
+++ b/activerecord/lib/active_record/result.rb
@@ -125,7 +125,7 @@ module ActiveRecord
           begin
             # We freeze the strings to prevent them getting duped when
             # used as keys in ActiveRecord::Base's @attributes hash
-            columns = @columns.map { |c| c.dup.freeze }
+            columns = @columns.map(&:-@)
             @rows.map { |row|
               # In the past we used Hash[columns.zip(row)]
               #  though elegant, the verbose way is much more efficient