1 files changed, 41 insertions, 0 deletions
diff --git a/rubocop/cop/migration/prevent_index_creation.rb b/rubocop/cop/migration/prevent_index_creation.rb
new file mode 100644
index 00000000000..c90f911d24e
--- /dev/null
+++ b/rubocop/cop/migration/prevent_index_creation.rb
@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+require_relative '../../migration_helpers'
+
+module RuboCop
+  module Cop
+    module Migration
+      # Cop that checks if new indexes are introduced to forbidden tables.
+      class PreventIndexCreation < RuboCop::Cop::Cop
+        include MigrationHelpers
+
+        FORBIDDEN_TABLES = %i[ci_builds].freeze
+
+        MSG = "Adding new index to #{FORBIDDEN_TABLES.join(", ")} is forbidden, see https://gitlab.com/gitlab-org/gitlab/-/issues/332886"
+
+        def_node_matcher :add_index?, <<~PATTERN
+          (send nil? :add_index (sym #forbidden_tables?) ...)
+        PATTERN
+
+        def_node_matcher :add_concurrent_index?, <<~PATTERN
+          (send nil? :add_concurrent_index (sym #forbidden_tables?) ...)
+        PATTERN
+
+        def forbidden_tables?(node)
+          FORBIDDEN_TABLES.include?(node)
+        end
+
+        def on_def(node)
+          return unless in_migration?(node)
+
+          node.each_descendant(:send) do |send_node|
+            add_offense(send_node, location: :selector) if offense?(send_node)
+          end
+        end
+
+        def offense?(node)
+          add_index?(node) || add_concurrent_index?(node)
+        end
+      end
+    end
+  end
+end