PERF: Add index to speed up ReindexSearch job (#20151)

db/migrate/20230202204937_add_index_to_posts_where_not_deleted_or_empty.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+class AddIndexToPostsWhereNotDeletedOrEmpty < ActiveRecord::Migration[7.0]
+  disable_ddl_transaction!
+
+  def up
+    execute <<~SQL
+      DROP INDEX CONCURRENTLY IF EXISTS index_posts_on_id_topic_id_where_not_deleted_or_empty
+    SQL
+
+    execute <<~SQL
+      CREATE INDEX CONCURRENTLY index_posts_on_id_topic_id_where_not_deleted_or_empty ON posts (id, topic_id) where deleted_at IS NULL AND raw <> ''
+    SQL
+  end
+
+  def down
+    execute <<~SQL
+      DROP INDEX IF EXISTS index_posts_on_id_topic_id_where_not_deleted_or_empty
+    SQL
+  end
+end