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)