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]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  def up
+    return unless Gitlab.staging?
+
+    # namespace ID 9970 is gitlab-org on staging.
+    with_lock_retries do
+      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
+  end
+
+  def down
+    return unless Gitlab.staging?
+
+    # namespace ID 9970 is gitlab-org on staging.
+    with_lock_retries do
+      execute(<<~SQL)
+        UPDATE
+          namespaces
+        SET
+          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
+      SQL
+    end
+  end
+end

db/schema_migrations/20210311045138

+01bbe2af2bc6bdaa6bf1e2fe10557e3f9f969cc60a348f188fbfe126ea7ea97d
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