add more gist indexes

closes CNVS-5180

Change-Id: Ib9d0db2d03c9c24f9536202e41cbeca4c2cd6b65
Reviewed-on: https://gerrit.instructure.com/26038
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Brian Palmer <brianp@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>

db/migrate/20131106171153_add_more_gist_indexes.rb

@@ -0,0 +1,21 @@
+class AddMoreGistIndexes < ActiveRecord::Migration
+  disable_ddl_transaction!
+  tag :predeploy
+
+  def self.up
+    if is_postgres? && has_postgres_proc?('show_trgm')
+      concurrently = " CONCURRENTLY" if connection.open_transactions == 0
+      execute("CREATE INDEX#{concurrently} index_trgm_users_short_name ON users USING gist(LOWER(short_name) gist_trgm_ops)")
+      execute("CREATE INDEX#{concurrently} index_trgm_courses_name ON courses USING gist(LOWER(name) gist_trgm_ops)")
+      execute("CREATE INDEX#{concurrently} index_trgm_courses_course_code ON courses USING gist(LOWER(course_code) gist_trgm_ops)")
+      execute("CREATE INDEX#{concurrently} index_trgm_courses_sis_source_id ON courses USING gist(LOWER(sis_source_id) gist_trgm_ops)")
+    end
+  end
+
+  def self.down
+    remove_index :users, name: 'index_trgm_users_short_name'
+    remove_index :courses, name: 'index_trgm_courses_name'
+    remove_index :courses, name: 'index_trgm_courses_course_code'
+    remove_index :courses, name: 'index_trgm_courses_sis_source_id'
+  end
+end