add index specifically supporting Submission.needs_grading

Change-Id: I9718a6f931f586b43c45f5505d0c6877eb3605ac Reviewed-on: https://gerrit.instructure.com/124526 Reviewed-by: Tyler Pickett <[email protected]> Tested-by: Jenkins Product-Review: Cody Cutrer <[email protected]> QA-Review: Cody Cutrer <[email protected]>
Joy603 · Aug 31, 2017 · 90a0167 · 90a0167
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Showing 2 changed files with 20 additions and 2 deletions.
diff --git a/app/models/submission.rb b/app/models/submission.rb
@@ -206,8 +206,8 @@ class Submission < ActiveRecord::Base
   end
 
   # see #needs_grading?
-  # When changing these conditions, consider updating index_submissions_on_assignment_id
-  # to maintain performance.
+  # When changing these conditions, update index_submissions_needs_grading to
+  # maintain performance.
   def self.needs_grading_conditions
     conditions = <<-SQL
       submissions.submission_type IS NOT NULL

diff --git a/db/migrate/20170830204122_add_submissions_needs_grading_index.rb b/db/migrate/20170830204122_add_submissions_needs_grading_index.rb
@@ -0,0 +1,18 @@
+class AddSubmissionsNeedsGradingIndex < ActiveRecord::Migration[5.0]
+  tag :postdeploy
+  disable_ddl_transaction!
+
+  def change
+    # see Submission.needs_grading; duplicated instead of called directly so the migration doesn't
+    # change even if the query does
+    add_index :submissions, :assignment_id, name: 'index_submissions_needs_grading', algorithm: :concurrently, where: <<-SQL
+      submissions.submission_type IS NOT NULL
+      AND (submissions.excused = 'f' OR submissions.excused IS NULL)
+      AND (submissions.workflow_state = 'pending_review'
+        OR (submissions.workflow_state IN ('submitted', 'graded')
+          AND (submissions.score IS NULL OR NOT submissions.grade_matches_current_submission)
+        )
+      )
+    SQL
+  end
+end