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MDL-8149 Added code to narrow down possibilities for get_my_courses, which reduces number of db queries required for profile page when site has many courses.

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sam_marshall 2007-01-12 17:05:32 +00:00
parent bcc113a304
commit f8e1c7af38
2 changed files with 73 additions and 4 deletions
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69
lib/datalib.php
View File

@ -670,19 +670,74 @@ function get_courses_page($categoryid="all", $sort="c.sortorder ASC", $fields="c
/**
* List of courses that a user is a member of.
* List of courses that a user has access to view. Note that for admins,
* this usually includes every course on the system.
*
* @uses $CFG
* @param int $userid The user of interest
* @param string $sort the sortorder in the course table
* @param string $fields the fields to return
* @param bool $doanything True if using the doanything flag
* @param int $limit Maximum number of records to return, or 0 for unlimited
* @return array {@link $COURSE} of course objects
*/
function get_my_courses($userid, $sort='visible DESC,sortorder ASC', $fields='*', $doanything=false) {
function get_my_courses($userid, $sort='visible DESC,sortorder ASC', $fields='*', $doanything=false,$limit=0) {
$mycourses = array();
// Fix fields to refer to the course table c
$fields=preg_replace('/([a-z0-9*]+)/','c.$1',$fields);
$rs = get_recordset('course', '', '', $sort, $fields);
// Attempt to filter the list of courses in order to reduce the number
// of queries in the next part.
// Check root permissions
$sitecontext = get_context_instance(CONTEXT_SYSTEM, SITEID);
if(has_capability('moodle/course:view',$sitecontext,$userid,$doanything)) {
// User can view all courses, although there might be exceptions
// which we will filter later.
$rs = get_recordset('course c', '', '', $sort, $fields);
} else {
// The only other context level above courses that applies to moodle/course:view
// is category. So we consider:
// 1. All courses in which the user is assigned a role
// 2. All courses in categories in which the user is assigned a role
// 3. All courses which have overrides for moodle/course:view
// Remember that this is just a filter. We check each individual course later.
// However for a typical student on a large system this can reduce the
// number of courses considered from around 2,000 to around 2, with corresponding
// reduction in the number of queries needed.
global $CFG;
$rs=get_recordset_sql("
SELECT
$fields
FROM
{$CFG->prefix}role_assignments ra
INNER JOIN {$CFG->prefix}context x ON x.id=ra.contextid
INNER JOIN {$CFG->prefix}course c ON x.instanceid=c.id AND x.contextlevel=50
WHERE
ra.userid=$userid
UNION
SELECT
$fields
FROM
{$CFG->prefix}role_assignments ra
INNER JOIN {$CFG->prefix}context x ON x.id=ra.contextid
INNER JOIN {$CFG->prefix}course_categories a ON x.instanceid=a.id AND x.contextlevel=40
INNER JOIN {$CFG->prefix}course c ON c.category=a.id
WHERE
ra.userid=$userid
UNION
SELECT
$fields
FROM
{$CFG->prefix}role_capabilities ca
INNER JOIN {$CFG->prefix}context x ON x.id=ca.contextid AND x.contextlevel=50
INNER JOIN {$CFG->prefix}course c ON c.id=x.instanceid
WHERE
ca.contextid <> {$sitecontext->id} AND ca.capability='moodle/course:view'
ORDER BY $sort");
}
if ($rs && $rs->RecordCount() > 0) {
while (!$rs->EOF) {
@ -697,6 +752,14 @@ function get_my_courses($userid, $sort='visible DESC,sortorder ASC', $fields='*'
!has_capability('moodle/legacy:guest', $context, $userid, false) &&
($course->visible || has_capability('moodle/course:viewhiddencourses', $context, $userid))) {
$mycourses[$course->id] = $course;
// Only return a limited number of courses if limit is set
if($limit>0) {
$limit--;
if($limit==0) {
break;
}
}
}
}

8
user/view.php
View File

@ -290,7 +290,8 @@
print_row(get_string('msnid').':', s($user->msn));
}
if ($mycourses = get_my_courses($user->id)) {
if ($mycourses = get_my_courses($user->id,'visible DESC,sortorder ASC', '*', false, 21)) {
$shown=0;
$courselisting = '';
foreach ($mycourses as $mycourse) {
if ($mycourse->visible and $mycourse->category) {
@ -301,6 +302,11 @@
$courselisting .= "$mycourse->fullname, ";
}
}
$shown++;
if($shown==20) {
$courselisting.= "...";
break;
}
}
print_row(get_string('courses').':', rtrim($courselisting,', '));
}