From a6bc93ae8f2b2f9ce89169722bf5861145883cef Mon Sep 17 00:00:00 2001
From: Tom Lanyon <tom@netspot.com.au>
Date: Wed, 9 May 2012 16:56:53 +0930
Subject: [PATCH 1/2] MDL-32931 mod_forum Change forum overview to avoid use of
 (potentially large and slow ) log table.

---
 mod/forum/lib.php | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/mod/forum/lib.php b/mod/forum/lib.php
index b1fd07e826043..035a9c043ba7d 100644
--- a/mod/forum/lib.php
+++ b/mod/forum/lib.php
@@ -1222,21 +1222,24 @@ function forum_print_overview($courses,&$htmlarray) {
     }
 
 
-    // get all forum logs in ONE query (much better!)
+    // look for new posts since lastaccess
+    $course_tuples = join(
+        ' OR ',
+        array_fill(0, count($visited_courses), '(f.course = ? AND p.created > ?)')
+    );
+
+    $sql = "SELECT f.id, COUNT(*) "
+                .'FROM {forum_posts} p, {forum_discussions} d, {forum} f '
+                .'WHERE p.discussion = d.id AND d.forum = f.id '
+                ."AND ($course_tuples) "
+                ."AND p.userid != ? "
+                ."GROUP BY f.id";
+
     $params = array();
-    $sql = "SELECT instance,cmid,l.course,COUNT(l.id) as count FROM {log} l "
-        ." JOIN {course_modules} cm ON cm.id = cmid "
-        ." WHERE (";
     foreach ($courses as $course) {
-        $sql .= '(l.course = ? AND l.time > ?) OR ';
         $params[] = $course->id;
         $params[] = $course->lastaccess;
     }
-    $sql = substr($sql,0,-3); // take off the last OR
-
-    $sql .= ") AND l.module = 'forum' AND action = 'add post' "
-        ." AND userid != ? GROUP BY cmid,l.course,instance";
-
     $params[] = $USER->id;
 
     if (!$new = $DB->get_records_sql($sql, $params)) {

From b729292ca3401c5052c891a6b47cbb3a4bb3c27b Mon Sep 17 00:00:00 2001
From: David Monllao <davidm@moodle.com>
Date: Mon, 9 Jul 2012 15:29:42 +0800
Subject: [PATCH 2/2] MDL-32931 mod_forum Polishing patch and taking into
 account courses without previous accesses

---
 mod/forum/lib.php | 39 +++++++++++++++++++++++----------------
 1 file changed, 23 insertions(+), 16 deletions(-)

diff --git a/mod/forum/lib.php b/mod/forum/lib.php
index 035a9c043ba7d..f42b6364eb134 100644
--- a/mod/forum/lib.php
+++ b/mod/forum/lib.php
@@ -1221,26 +1221,33 @@ function forum_print_overview($courses,&$htmlarray) {
         return;
     }
 
-
-    // look for new posts since lastaccess
-    $course_tuples = join(
-        ' OR ',
-        array_fill(0, count($visited_courses), '(f.course = ? AND p.created > ?)')
-    );
-
-    $sql = "SELECT f.id, COUNT(*) "
-                .'FROM {forum_posts} p, {forum_discussions} d, {forum} f '
-                .'WHERE p.discussion = d.id AND d.forum = f.id '
-                ."AND ($course_tuples) "
-                ."AND p.userid != ? "
-                ."GROUP BY f.id";
-
+    // Courses to search for new posts
+    $coursessqls = array();
     $params = array();
     foreach ($courses as $course) {
-        $params[] = $course->id;
-        $params[] = $course->lastaccess;
+
+        // If the user has never entered into the course all posts are pending
+        if ($course->lastaccess == 0) {
+            $coursessqls[] = '(f.course = ?)';
+            $params[] = $course->id;
+
+        // Only posts created after the course last access
+        } else {
+            $coursessqls[] = '(f.course = ? AND p.created > ?)';
+            $params[] = $course->id;
+            $params[] = $course->lastaccess;
+        }
     }
     $params[] = $USER->id;
+    $coursessql = implode(' OR ', $coursessqls);
+
+    $sql = "SELECT f.id, COUNT(*) as count "
+                .'FROM {forum} f '
+                .'JOIN {forum_discussions} d ON d.forum  = f.id '
+                .'JOIN {forum_posts} p ON p.discussion = d.id '
+                ."WHERE ($coursessql) "
+                .'AND p.userid != ? '
+                .'GROUP BY f.id';
 
     if (!$new = $DB->get_records_sql($sql, $params)) {
         $new = array(); // avoid warnings