PERF: Preload only gists when including summaries in topic list

Author: romanrizzi

lib/summarization/entry_point.rb

@@ -20,7 +20,7 @@ def inject_into(plugin)
         plugin.register_modifier(:topic_query_create_list_topics) do |topics, options|
           if Discourse.filters.include?(options[:filter]) && SiteSetting.ai_summarization_enabled &&
                SiteSetting.ai_summarize_max_hot_topics_gists_per_batch > 0
-            topics.includes(:ai_summaries)
+            topics.includes(:ai_gist_summary)
           else
             topics
           end
@@ -32,11 +32,7 @@ def inject_into(plugin)
           include_condition: -> { scope.can_see_gists? },
         ) do
           return if !Discourse.filters.include?(options[:filter])
-          summaries = object.ai_summaries.to_a
-
-          # Summaries should always have one or zero elements here.
-          # This is an extra safeguard to avoid including regular summaries.
-          summaries.find { |s| s.summary_type == "gist" }&.summarized_text
+          object.ai_gist_summary&.summarized_text
         end
 
         # To make sure hot topic gists are inmediately up to date, we rely on this event

lib/topic_extensions.rb

@@ -4,6 +4,13 @@ module DiscourseAi
   module TopicExtensions
     extend ActiveSupport::Concern
 
-    prepended { has_many :ai_summaries, as: :target }
+    prepended do
+      has_many :ai_summaries, as: :target
+
+      has_one :ai_gist_summary,
+              -> { where(summary_type: AiSummary.summary_types[:gist]) },
+              class_name: "AiSummary",
+              as: :target
+    end
   end
 end