Get rid of pluck in app/services/members/authorized_destroy_service.rb

app/services/members/authorized_destroy_service.rb

@@ -26,10 +26,14 @@ module Members
     def unassign_issues_and_merge_requests(member)
       if member.is_a?(GroupMember)
-        issue_ids = IssuesFinder.new(user, group_id: member.source_id, assignee_id: member.user_id).
-          execute.pluck(:id)
-        IssueAssignee.delete_all(issue_id: issue_ids, user_id: member.user_id)
+        issues = Issue.unscoped.select(1).
+                 joins(:project).
+                 where('issues.id = issue_assignees.issue_id AND projects.namespace_id = ?', member.source_id)
+        # DELETE FROM issue_assignees WHERE user_id = X AND EXISTS (...)
+        IssueAssignee.unscoped.
+          where('user_id = :user_id AND EXISTS (:sub)', user_id: member.user_id, sub: issues).
+          delete_all
         MergeRequestsFinder.new(user, group_id: member.source_id, assignee_id: member.user_id).
           execute.

changelogs/unreleased/get_rid_of_pluck.yml

+---
+title: Issue assignees are now removed without loading unnecessary data into memory
+merge_request:
+author: