Add latest changes from gitlab-org/gitlab@13-3-stable-ee

1 files changed, 43 insertions, 0 deletions

diff --git a/rubocop/cop/usage_data/distinct_count_by_large_foreign_key.rb b/rubocop/cop/usage_data/distinct_count_by_large_foreign_key.rb
new file mode 100644
index 00000000000..c10ecbcb4ba
--- /dev/null
+++ b/rubocop/cop/usage_data/distinct_count_by_large_foreign_key.rb
@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module UsageData
+      # Allows counts only for selected tables' foreign keys for `distinct_count` method.
+      #
+      # Because distinct_counts over large tables' foreign keys will take a long time
+      #
+      # @example
+      #
+      #   # bad because pipeline_id points to a large table
+      #   distinct_count(Ci::Build, :commit_id)
+      #
+      class DistinctCountByLargeForeignKey < RuboCop::Cop::Cop
+        MSG = 'Avoid doing `%s` on foreign keys for large tables having above 100 million rows.'.freeze
+
+        def_node_matcher :distinct_count?, <<-PATTERN
+          (send _ $:distinct_count $...)
+        PATTERN
+
+        def on_send(node)
+          distinct_count?(node) do |method_name, method_arguments|
+            next unless method_arguments && method_arguments.length >= 2
+            next if allowed_foreign_key?(method_arguments[1])
+
+            add_offense(node, location: :selector, message: format(MSG, method_name))
+          end
+        end
+
+        private
+
+        def allowed_foreign_key?(key)
+          key.type == :sym && allowed_foreign_keys.include?(key.value)
+        end
+
+        def allowed_foreign_keys
+          cop_config['AllowedForeignKeys'] || []
+        end
+      end
+    end
+  end
+end