discourse/db/migrate/20220727040437_add_topic_timers_index.rb

# frozen_string_literal: true

class AddTopicTimersIndex < ActiveRecord::Migration[7.0]
  def change
    add_index :topic_timers, [:topic_id], where: "deleted_at IS NULL"
  end
end
PERF: Add index for TopicTimer#topic_id (#17680) When viewing a topic, we execute two queries to fetch the topic's public topic timer and slow mode timer. The former query happens to be able to use a unique index but the latter has to do a seq scan which is slow. The query itself is not expensive but since viewing a topic is a hot path, the little cuts add up overtime and the query itself contributes significantly to the load of the database. 2022-07-27 16:21:11 +08:00			`# frozen_string_literal: true`

			`class AddTopicTimersIndex < ActiveRecord::Migration[7.0]`
			`def change`
			`add_index :topic_timers, [:topic_id], where: "deleted_at IS NULL"`
			`end`
			`end`