Add table for merge request commits

This is an ID-less table with just three columns: an association to the merge
request diff the commit belongs to, the relative order of the commit within the
merge request diff, and the commit SHA itself.

Previously we stored much more information about the commits, so that we could
display them even when they were deleted from the repo. Since 8.0, we ensure
that those commits are kept around for as long as the target repo itself is, so
we don't need to duplicate that data in the database.

1 files changed, 5 insertions, 5 deletions

diff --git a/app/models/merge_request.rb b/app/models/merge_request.rb
index 2752181ed79..2fc6191e785 100644
--- a/app/models/merge_request.rb
+++ b/app/models/merge_request.rb
@@ -31,7 +31,7 @@ class MergeRequest < ActiveRecord::Base
   after_create :ensure_merge_request_diff, unless: :importing?
   after_update :reload_diff_if_branch_changed
 
-  delegate :commits, :real_size, :commits_sha, :commits_count,
+  delegate :commits, :real_size, :commit_shas, :commits_count,
     to: :merge_request_diff, prefix: nil
 
   # When this attribute is true some MR validation is ignored
@@ -518,7 +518,7 @@ class MergeRequest < ActiveRecord::Base
   def related_notes
     # Fetch comments only from last 100 commits
     commits_for_notes_limit = 100
-    commit_ids = commits.last(commits_for_notes_limit).map(&:id)
+    commit_ids = commit_shas.take(commits_for_notes_limit)
 
     Note.where(
       "(project_id = :target_project_id AND noteable_type = 'MergeRequest' AND noteable_id = :mr_id) OR" +
@@ -841,15 +841,15 @@ class MergeRequest < ActiveRecord::Base
     return Ci::Pipeline.none unless source_project
 
     @all_pipelines ||= source_project.pipelines
-      .where(sha: all_commits_sha, ref: source_branch)
+      .where(sha: all_commit_shas, ref: source_branch)
       .order(id: :desc)
   end
 
   # Note that this could also return SHA from now dangling commits
   #
-  def all_commits_sha
+  def all_commit_shas
     if persisted?
-      merge_request_diffs.flat_map(&:commits_sha).uniq
+      merge_request_diffs.preload(:merge_request_diff_commits).flat_map(&:commit_shas).uniq
     elsif compare_commits
       compare_commits.to_a.reverse.map(&:id)
     else