General developer forum

We have encountered the same problem on our production system (Moodle 1.8.9, MySQL). "sort by names" did not work, using the arrows did not change the sortorder.

As mentioned in previous answers, the reason is an overflow in the "sortorder" field of the mdl_course table. Even if SQL can handle the large numbers, PHP can not. In our case, the sortorder reached values over 13666533340000000000, which is really large!

At first, we fixed the problem with an SQL-Statement:
update mdl_course set sortorder=sortorder -  13666533340000000000 where sortorder >=  13666533340000000000;

Then, we searched the source code and stumbled over the "fix_course_sortorder()" function in lib/datalib.php, which is called every time the courses of a category are sorted. To be honest, I do not very like the way this function works. E.g., there is a "catgap" value of 1000 wired into the source code. When every category has its own sortorder, why do we need a catgap?

But the main thing is the following:
<snip>
      // $mustshift indicates whether the sequence must be shifted to
    // meet its range
    $mustshift = false;
    if ($min < $n+$tolerance || $min > $n+$tolerance+$catgap ) {
        $mustshift = true;
    }
<snip>

$n is normally set to $min some lines above, so $min will be less than $n+$tolerance, wouldn`t it? So every time the function is called the sortorder wull be shiftet by that $catgap of 1000. It is only a matter of time when it will overflow!

We changed that part, here is the diff:

    // $mustshift indicates whether the sequence must be shifted to
    // meet its range
    $mustshift = false;
-    if ($min < $n+$tolerance || $min > $n+$tolerance+$catgap ) {
+    if ($min < $n-$tolerance || $max > $n+$tolerance+$catgap ) {
        $mustshift = true;
    }

There is another minor problem with the calculation of the course order in course/category, here is the diff:

@@ -77,9 +77,16 @@
        if ($resort and confirm_sesskey()) {
            if ($courses = get_courses($category->id, "fullname ASC", 'c.id,c.fullname,c.sortorder')) {
                // move it off the range
-                $count = get_record_sql('SELECT MAX(sortorder) AS max, 1
+                # rherbst - must there be a shift of 100 for every sorting?
+                # old
+                # $count = get_record_sql('SELECT MAX(sortorder) AS max, 1
+                #                          FROM ' . $CFG->prefix . 'course WHERE category=' . $category->id);
+                #  $count = $count->max + 100;
+
+                # new
+                $count = get_record_sql('SELECT MIN(sortorder) AS min, 1
                                          FROM ' . $CFG->prefix . 'course WHERE category=' . $category->id);
-                $count = $count->max + 100;
+                $count = $count->min;
                begin_sql();
                foreach ($courses as $course) {
                    set_field('course', 'sortorder', $count, 'id', $course->id);


In the old version, every time you clicked "resort by names"-button, the sortorder will increase in steps of 100. In the new version, we will start with the minimum sortorder value and increase the value by one for the next course.

Untill yet, everything seems to work correctly on our test and production system.

As far as I know, version 1.8.x will not receive bug fixes, so I will not bother to create a bug tracker entry. Hope the diffs show you what do do!

hello,
I have the same problem on my moodle and no solutions!!! no help on the french forum