Only load branch names for protected branch checks

When checking if a branch is protected we don't need all columns of
every protected branch row, instead we only care about the names. By
using "select" here we reduce the amount of data we need to send over
the wire and load into memory.

app/models/protected_branch.rb

@@ -10,7 +10,9 @@ class ProtectedBranch < ActiveRecord::Base
   def self.protected?(project, ref_name)
     return true if project.empty_repo? && default_branch_protected?
 
-    self.matching(ref_name, protected_refs: project.protected_branches).present?
+    refs = project.protected_branches.select(:name)
+
+    self.matching(ref_name, protected_refs: refs).present?
   end
 
   def self.default_branch_protected?

app/models/protected_tag.rb

@@ -5,6 +5,8 @@ class ProtectedTag < ActiveRecord::Base
   protected_ref_access_levels :create
 
   def self.protected?(project, ref_name)
-    self.matching(ref_name, protected_refs: project.protected_tags).present?
+    refs = project.protected_tags.select(:name)
+
+    self.matching(ref_name, protected_refs: refs).present?
   end
 end

changelogs/unreleased/protected-branches-names.yml

@@ -0,0 +1,5 @@
+---
+title: Only load branch names for protected branch checks
+merge_request:
+author:
+type: performance