From 8c32bd8d525a49564015ad6ec7a81dd508b2e753 Mon Sep 17 00:00:00 2001
From: Brian Williams <bwilliams@gitlab.com>
Date: Wed, 17 Dec 2025 11:37:27 -0600
Subject: [PATCH] Remove BackfillSecurityProjectTrackedContextsDefaultBranch
 migration

This migration turned out to be very slow because it makes N+1 Gitaly
calls. At the current rate, the GitLab.com migration will complete in
about 2 years. Since migrations block GitLab upgrades and this is too
slow, we need to remove it.

Changelog: removed
---
 ..._project_tracked_contexts_default_branch.rb | 18 ++----------------
 ..._project_tracked_contexts_default_branch.rb | 16 ++++++++++++++++
 db/schema_migrations/20251217173006            |  1 +
 3 files changed, 19 insertions(+), 16 deletions(-)
 create mode 100644 db/post_migrate/20251217173006_remove_backfill_security_project_tracked_contexts_default_branch.rb
 create mode 100644 db/schema_migrations/20251217173006

diff --git a/db/post_migrate/20251205211140_queue_backfill_security_project_tracked_contexts_default_branch.rb b/db/post_migrate/20251205211140_queue_backfill_security_project_tracked_contexts_default_branch.rb
index 2dfb588a5d63da..3d7f4aa9abf2d9 100644
--- a/db/post_migrate/20251205211140_queue_backfill_security_project_tracked_contexts_default_branch.rb
+++ b/db/post_migrate/20251205211140_queue_backfill_security_project_tracked_contexts_default_branch.rb
@@ -4,23 +4,9 @@ class QueueBackfillSecurityProjectTrackedContextsDefaultBranch < Gitlab::Databas
   milestone '18.7'
   restrict_gitlab_migration gitlab_schema: :gitlab_main_org
 
-  MIGRATION = "BackfillSecurityProjectTrackedContextsDefaultBranch"
-  DELAY_INTERVAL = 2.minutes
-  BATCH_SIZE = 1000
-  SUB_BATCH_SIZE = 100
-
   def up
-    queue_batched_background_migration(
-      MIGRATION,
-      :projects,
-      :id,
-      job_interval: DELAY_INTERVAL,
-      batch_size: BATCH_SIZE,
-      sub_batch_size: SUB_BATCH_SIZE
-    )
+    # This migration is removed by migration 20251217173006 because it is very slow.
   end
 
-  def down
-    delete_batched_background_migration(MIGRATION, :projects, :id, [])
-  end
+  def down; end
 end
diff --git a/db/post_migrate/20251217173006_remove_backfill_security_project_tracked_contexts_default_branch.rb b/db/post_migrate/20251217173006_remove_backfill_security_project_tracked_contexts_default_branch.rb
new file mode 100644
index 00000000000000..762b7c311138e7
--- /dev/null
+++ b/db/post_migrate/20251217173006_remove_backfill_security_project_tracked_contexts_default_branch.rb
@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+class RemoveBackfillSecurityProjectTrackedContextsDefaultBranch < Gitlab::Database::Migration[2.3]
+  milestone '18.8'
+  restrict_gitlab_migration gitlab_schema: :gitlab_main_org
+
+  MIGRATION = "BackfillSecurityProjectTrackedContextsDefaultBranch"
+
+  def up
+    delete_batched_background_migration(MIGRATION, :projects, :id, [])
+  end
+
+  def down
+    # no-op
+  end
+end
diff --git a/db/schema_migrations/20251217173006 b/db/schema_migrations/20251217173006
new file mode 100644
index 00000000000000..575a945c3b104e
--- /dev/null
+++ b/db/schema_migrations/20251217173006
@@ -0,0 +1 @@
+d5f7b6ca821ad5b3f77801366e3c9bbaa1e47979cdd7cbe3170be2bb777a2b5f
\ No newline at end of file
-- 
GitLab