feat: improve article search ranking (#11640)

app/models/article.rb

@@ -76,18 +76,24 @@ class Article < ApplicationRecord
   scope :order_by_views, -> { reorder(views: :desc) }
 
   # TODO: if text search slows down https://www.postgresql.org/docs/current/textsearch-features.html#TEXTSEARCH-UPDATE-TRIGGERS
+  # - the A, B and C are for weightage. See: https://github.com/Casecommons/pg_search#weighting
+  # - the normalization is for ensuring the long articles that mention the search term too many times are not ranked higher.
+  #   it divides rank by log(document_length) to prevent longer articles from ranking higher just due to sizeSee: https://github.com/Casecommons/pg_search#normalization
+  # - the ranking is to ensure that articles with higher weightage are ranked higher
   pg_search_scope(
     :text_search,
-    against: %i[
-      title
-      description
-      content
-    ],
+    against: {
+      title: 'A',
+      description: 'B',
+      content: 'C'
+    },
     using: {
       tsearch: {
-        prefix: true
+        prefix: true,
+        normalization: 2
       }
-    }
+    },
+    ranked_by: ':tsearch'
   )
 
   def self.search(params)

app/services/search_service.rb

@@ -96,7 +96,6 @@ class SearchService
   def filter_articles
     @articles = current_account.articles
                                .text_search(search_query)
-                               .reorder('updated_at DESC')
                                .page(params[:page])
                                .per(15)
   end

spec/services/search_service_spec.rb

@@ -156,33 +156,18 @@ describe SearchService do
     end
 
     context 'when article search' do
-      it 'orders results by updated_at desc' do
-        # Create articles with explicit timestamps
-        older_time = 2.days.ago
-        newer_time = 1.hour.ago
-
+      it 'returns matching articles' do
         article2 = create(:article, title: 'Spellcasting Guide',
                                     account: account, portal: portal, author: user, status: 'published')
-        # rubocop:disable Rails/SkipsModelValidations
-        article2.update_column(:updated_at, older_time)
-        # rubocop:enable Rails/SkipsModelValidations
-
         article3 = create(:article, title: 'Spellcasting Manual',
                                     account: account, portal: portal, author: user, status: 'published')
-        # rubocop:disable Rails/SkipsModelValidations
-        article3.update_column(:updated_at, newer_time)
-        # rubocop:enable Rails/SkipsModelValidations
 
         params = { q: 'Spellcasting' }
         search = described_class.new(current_user: user, current_account: account, params: params, search_type: 'Article')
         results = search.perform[:articles]
 
-        # Check the timestamps to understand ordering
-        results.map { |a| [a.id, a.updated_at] }
-
-        # Should be ordered by updated_at desc (newer first)
         expect(results.length).to eq(2)
-        expect(results.first.updated_at).to be > results.second.updated_at
+        expect(results.map(&:id)).to contain_exactly(article2.id, article3.id)
       end
 
       it 'returns paginated results' do