Creates rake task for refreshing the full text materialized view

README.markdown

@@ -23,3 +23,10 @@ When developing the LTI tool provider components of Gala, it is useful to be abl
 1. Trust the certificate on your host machine using Keychain Access. Drag `localhost.crt` into the app, then Get Info and choose Always Trust.
 1. Start the development servers with `LOCALHOST_SSL=true foreman start`
 1. Browse to https://localhost:3000 (http will not work)
+
+## Cron jobs
+
+The full-text case search is powered by a Postgres materialized view so it’s
+really fast. The consequence is that changes don’t appear in search results
+until the view is refreshed. Set a cron job or use Heroku Scheduler or the
+equivalent to run `rake indices:refresh` as frequently as makes sense.

db/migrate/20171031161433_create_english_cases_search_index.rb

@@ -54,6 +54,8 @@ def up
         LEFT JOIN cards ON cards.case_id = pages.id
        GROUP BY cases.id;
 
+      CREATE UNIQUE INDEX index_cases_search_index_en ON cases_search_index_en
+             USING btree(id);
       CREATE INDEX index_cases_on_english_full_text ON cases_search_index_en
              USING gin(document);
     SQL
@@ -62,6 +64,7 @@ def up
   def down
     execute <<~SQL
       DROP INDEX index_cases_on_english_full_text;
+      DROP INDEX index_cases_search_index_en;
       DROP MATERIALIZED VIEW cases_search_index_en;
     SQL
   end

db/structure.sql

@@ -1582,6 +1582,13 @@ CREATE UNIQUE INDEX index_cases_on_slug ON cases USING btree (slug);
 CREATE INDEX index_cases_on_tags ON cases USING gin (tags);
 
 
+--
+-- Name: index_cases_search_index_en; Type: INDEX; Schema: public; Owner: -
+--
+
+CREATE UNIQUE INDEX index_cases_search_index_en ON cases_search_index_en USING btree (id);
+
+
 --
 -- Name: index_comment_threads_on_card_id; Type: INDEX; Schema: public; Owner: -
 --

lib/tasks/indices.rake

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+namespace :indices do
+  desc 'Refresh the index for full-text searching of cases'
+  task refresh: :environment do
+    ActiveRecord::Base.connection.execute <<~SQL
+      REFRESH MATERIALIZED VIEW CONCURRENTLY cases_search_index_en;
+    SQL
+  end
+end