1 files changed, 53 insertions, 0 deletions
diff --git a/rubocop/cop/database/avoid_using_pluck_without_limit.rb b/rubocop/cop/database/avoid_using_pluck_without_limit.rb
new file mode 100644
index 00000000000..8f1ea251dcb
--- /dev/null
+++ b/rubocop/cop/database/avoid_using_pluck_without_limit.rb
@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+require 'rubocop/cop/mixin/active_record_helper'
+require_relative '../../code_reuse_helpers'
+
+module RuboCop
+  module Cop
+    module Database
+      # Checks the use of .pluck(:attribute) without setting a limit.
+      #
+      # @example
+      #
+      #   # bad
+      #   def all
+      #     Project.where(user_id: User.pluck(:id))
+      #   end
+      #
+      #   # good
+      #   def all(limit)
+      #     Project.where(user_id: User.limit(limit).pluck(:id))
+      #   end
+      class AvoidUsingPluckWithoutLimit < RuboCop::Cop::Base
+        include RuboCop::Cop::ActiveRecordHelper
+        include RuboCop::CodeReuseHelpers
+
+        MSG = 'Avoid using `pluck` without defining a proper `limit`. ' \
+              'Querying with too much values inside an `IN` clause can result in database performance degradation. ' \
+              'See https://gitlab.com/gitlab-com/gl-infra/production/-/issues/17168'
+
+        RESTRICT_ON_SEND = %i[pluck].freeze
+
+        def_node_matcher :pluck_with_limit?, <<~PATTERN
+        (send (send _ :limit _) ...)
+        PATTERN
+
+        def on_send(node)
+          return unless should_scan?(node)
+
+          return if pluck_with_limit?(node)
+
+          add_offense(node.loc.selector)
+        end
+
+        private
+
+        # It limits the check to ActiveRecord, Models, Finders and Service classes
+        def should_scan?(node)
+          inherit_active_record_base?(node) || in_model?(node) || in_finder?(node) || in_service_class?(node)
+        end
+      end
+    end
+  end
+end