Optimize markdown rendering in search results

app/helpers/search_helper.rb

@@ -250,15 +250,16 @@ module SearchHelper
 
   # Sanitize a HTML field for search display. Most tags are stripped out and the
   # maximum length is set to 200 characters.
-  def search_md_sanitize(object, field)
-    html = markdown_field(object, field)
-    html = Truncato.truncate(
-      html,
+  def search_md_sanitize(source)
+    source = Truncato.truncate(
+      source,
       count_tags: false,
       count_tail: false,
       max_length: 200
     )
 
+    html = markdown(source)
+
     # Truncato's filtered_tags and filtered_attributes are not quite the same
     sanitize(html, tags: %w(a p ol ul li pre code))
   end

app/views/search/results/_issue.html.haml

@@ -8,6 +8,6 @@
     .float-right ##{issue.iid}
   - if issue.description.present?
     .description.term
-      = search_md_sanitize(issue, :description)
+      = search_md_sanitize(issue.description)
   %span.light
     #{issue.project.full_name}

app/views/search/results/_merge_request.html.haml

@@ -9,6 +9,6 @@
     .float-right= merge_request.to_reference
   - if merge_request.description.present?
     .description.term
-      = search_md_sanitize(merge_request, :description)
+      = search_md_sanitize(merge_request.description)
   %span.light
     #{merge_request.project.full_name}

app/views/search/results/_milestone.html.haml

@@ -5,4 +5,4 @@
 
   - if milestone.description.present?
     .description.term
-      = search_md_sanitize(milestone, :description)
+      = search_md_sanitize(milestone.description)

app/views/search/results/_note.html.haml

@@ -22,4 +22,4 @@
 
   .note-search-result
     .term
-      = search_md_sanitize(note, :note)
+      = search_md_sanitize(note.note)

changelogs/unreleased/233301-search-markdown-rendering-queries.yml

+---
+title: Optimize markdown rendering in search results
+merge_request: 39833
+author:
+type: performance

spec/helpers/search_helper_spec.rb

@@ -3,6 +3,8 @@
 require 'spec_helper'
 
 RSpec.describe SearchHelper do
+  include MarkupHelper
+
   # Override simple_sanitize for our testing purposes
   def simple_sanitize(str)
     str
@@ -228,6 +230,20 @@ RSpec.describe SearchHelper do
     end
   end
 
+  describe 'search_md_sanitize' do
+    it 'does not do extra sql queries for partial markdown rendering' do
+      @project = create(:project)
+
+      description = FFaker::Lorem.characters(210)
+      control_count = ActiveRecord::QueryRecorder.new(skip_cached: false) { search_md_sanitize(description) }.count
+
+      issues = create_list(:issue, 4, project: @project)
+
+      description_with_issues = description + ' ' + issues.map { |issue| "##{issue.iid}" }.join(' ')
+      expect { search_md_sanitize(description_with_issues) }.not_to exceed_all_query_limit(control_count)
+    end
+  end
+
   describe 'search_filter_link' do
     it 'renders a search filter link for the current scope' do
       @scope = 'projects'