1 files changed, 40 insertions, 0 deletions
diff --git a/lib/gitlab/background_migration/backfill_upvotes_count_on_issues.rb b/lib/gitlab/background_migration/backfill_upvotes_count_on_issues.rb
new file mode 100644
index 00000000000..170af90805a
--- /dev/null
+++ b/lib/gitlab/background_migration/backfill_upvotes_count_on_issues.rb
@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module BackgroundMigration
+    # Class that will populate the upvotes_count field
+    # for each issue
+    class BackfillUpvotesCountOnIssues
+      BATCH_SIZE = 1_000
+
+      def perform(start_id, stop_id)
+        (start_id..stop_id).step(BATCH_SIZE).each do |offset|
+          update_issue_upvotes_count(offset, offset + BATCH_SIZE)
+        end
+      end
+
+      private
+
+      def execute(sql)
+        @connection ||= ::ActiveRecord::Base.connection
+        @connection.execute(sql)
+      end
+
+      def update_issue_upvotes_count(batch_start, batch_stop)
+        execute(<<~SQL)
+          UPDATE issues
+          SET upvotes_count = sub_q.count_all
+          FROM (
+            SELECT COUNT(*) AS count_all, e.awardable_id AS issue_id
+            FROM award_emoji AS e
+            WHERE e.name = 'thumbsup' AND
+            e.awardable_type = 'Issue' AND
+            e.awardable_id BETWEEN #{batch_start} AND #{batch_stop}
+            GROUP BY issue_id
+          ) AS sub_q
+          WHERE sub_q.issue_id = issues.id;
+        SQL
+      end
+    end
+  end
+end