MDL-14208 "add cron routine to clean up cache records"

mod/quiz/report/statistics/cron.php

+<?php  // $Id$
+function quiz_report_statistics_cron(){
+    global $DB;
+    if ($todelete = $DB->get_records_select_menu('quiz_statistics', 'timemodified < ?', array(time()-5*HOURSECS))){
+        list($todeletesql, $todeleteparams) = $DB->get_in_or_equal($todelete);
+        if (!$DB->delete_records_select('quiz_statistics', "id $todeletesql", $todeleteparams)){
+            mtrace('Error deleting out of date quiz_statistics records.');
+        }
+        if (!$DB->delete_records_select('quiz_question_statistics', "quizstatisticsid $todeletesql", $todeleteparams)){
+            mtrace('Error deleting out of date quiz_question_statistics records.');
+        }
+    }
+    return true;
+}
+?>

mod/quiz/report/statistics/db/upgrade.php

+<?php  // $Id$
+
+function xmldb_quizreport_statistics_upgrade($oldversion=0) {
+
+    global $DB;
+    
+    $dbman = $DB->get_manager();
+
+    $result = true;
+
+//===== 1.9.0 upgrade line ======//
+
+    if ($result && $oldversion < 2008072401) {
+        //register cron to run every 5 hours.
+        $result = $result && $DB->set_field('quiz_report', 'cron', HOURSECS*5, array('name'=>'statistics'));
+    }
+    return $result;
+}
+
+?>

mod/quiz/report/statistics/version.php

 <?php
-$plugin->version  = 2008072400;   // The (date) version of this module
+$plugin->version  = 2008072401;   // The (date) version of this module
 
 ?>
\ No newline at end of file