1 files changed, 22 insertions, 18 deletions
diff --git a/app/models/merge_request_diff.rb b/app/models/merge_request_diff.rb
index fb873ddbbab..2dc6796732f 100644
--- a/app/models/merge_request_diff.rb
+++ b/app/models/merge_request_diff.rb
@@ -113,14 +113,29 @@ class MergeRequestDiff < ApplicationRecord
     joins(merge_request: :metrics).where(condition)
   end
 
+  # This scope uses LATERAL JOIN to find the most recent MR diff association for the given merge requests.
+  # To avoid joining the merge_requests table, we build an in memory table using the merge request ids.
+  # Example:
+  # SELECT ...
+  # FROM (VALUES (MR_ID_1),(MR_ID_2)) merge_requests (id)
+  # INNER JOIN LATERAL (...)
   scope :latest_diff_for_merge_requests, -> (merge_requests) do
-    inner_select = MergeRequestDiff
-      .default_scoped
-      .distinct
-      .select("FIRST_VALUE(id) OVER (PARTITION BY merge_request_id ORDER BY created_at DESC) as id")
-      .where(merge_request: merge_requests)
+    mrs = Array(merge_requests)
+    return MergeRequestDiff.none if mrs.empty?
 
-    joins("INNER JOIN (#{inner_select.to_sql}) latest_diffs ON latest_diffs.id = merge_request_diffs.id")
+    merge_request_table = MergeRequest.arel_table
+    merge_request_diff_table = MergeRequestDiff.arel_table
+
+    join_query = MergeRequestDiff
+      .where(merge_request_table[:id].eq(merge_request_diff_table[:merge_request_id]))
+      .order(created_at: :desc)
+      .limit(1)
+
+    mr_id_list = mrs.map { |mr| "(#{Integer(mr.id)})" }.join(",")
+
+    MergeRequestDiff
+      .from("(VALUES #{mr_id_list}) merge_requests (id)")
+      .joins("INNER JOIN LATERAL (#{join_query.to_sql}) #{MergeRequestDiff.table_name} ON TRUE")
       .includes(:merge_request_diff_commits)
   end
 
@@ -665,10 +680,6 @@ class MergeRequestDiff < ApplicationRecord
     opening_external_diff do
       collection = merge_request_diff_files
 
-      if options[:include_context_commits]
-        collection += merge_request.merge_request_context_commit_diff_files
-      end
-
       if paths = options[:paths]
         collection = collection.where('old_path IN (?) OR new_path IN (?)', paths, paths)
       end
@@ -743,7 +754,6 @@ class MergeRequestDiff < ApplicationRecord
   end
 
   def reorder_diff_files!
-    return unless sort_diffs?
     return if sorted? || merge_request_diff_files.empty?
 
     diff_files = sort_diffs(merge_request_diff_files)
@@ -762,14 +772,8 @@ class MergeRequestDiff < ApplicationRecord
   end
 
   def sort_diffs(diffs)
-    return diffs unless sort_diffs?
-
     Gitlab::Diff::FileCollectionSorter.new(diffs).sort
   end
-
-  def sort_diffs?
-    Feature.enabled?(:sort_diffs, project, default_enabled: :yaml)
-  end
 end
 
-MergeRequestDiff.prepend_if_ee('EE::MergeRequestDiff')
+MergeRequestDiff.prepend_mod_with('MergeRequestDiff')