Backfill traversal_ids for gitlab-org staging

This migration only applies to staging.

changelogs/unreleased/233431-set-traversal_ids-for-gitlab-org-group.yml

+---
+title: Backfill traversal_ids for gitlab-org staging
+merge_request: 56293
+author:
+type: performance

db/post_migrate/20210311045138_set_traversal_ids_for_gitlab_org_group_staging.rb

+# frozen_string_literal: true
+
+class SetTraversalIdsForGitlabOrgGroupStaging < ActiveRecord::Migration[6.0]
+  DOWNTIME = false
+
+  def up
+    return unless Gitlab.staging?
+
+    # namespace ID 9970 is gitlab-org on staging.
+    execute(<<~SQL)
+      UPDATE
+        namespaces
+      SET
+        traversal_ids = cte.traversal_ids
+      FROM
+        (
+          WITH RECURSIVE cte(id, traversal_ids, cycle) AS (
+            VALUES
+              (9970, ARRAY[9970], false)
+            UNION ALL
+            SELECT
+              n.id,
+              cte.traversal_ids || n.id,
+              n.id = ANY(cte.traversal_ids)
+            FROM
+              namespaces n,
+              cte
+            WHERE
+              n.parent_id = cte.id
+              AND NOT cycle
+          )
+          SELECT
+            id,
+            traversal_ids
+          FROM
+            cte FOR
+          UPDATE
+            ) as cte
+      WHERE
+        namespaces.id = cte.id
+        AND namespaces.traversal_ids <> cte.traversal_ids
+    SQL
+  end
+
+  # We can't reverse this data migration.
+  # This method intentionally left blank.
+  # def down
+  # end
+end

db/schema_migrations/20210311045138

+01bbe2af2bc6bdaa6bf1e2fe10557e3f9f969cc60a348f188fbfe126ea7ea97d
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