- Patch #243093 by catch, killes: improved indices on comment table.

modules/comment/comment.install

@@ -153,6 +153,18 @@ function comment_update_7002() {
   return $ret;
 }
 
+/**
+ * Improve indexes on the comment table.
+ */
+function comment_update_7003() {
+  $ret = array();
+  db_drop_index($ret, 'comment', 'status');
+  db_drop_index($rest, 'comment', 'pid');
+  db_add_index($ret, 'comment', 'comment_pid_status', array('pid', 'status'));
+  db_add_index($ret, 'comment', 'comment_num_new', array('nid', 'timestamp', 'status'));
+  return $ret;
+}
+
 /**
  * @} End of "defgroup updates-6.x-to-7.x"
  * The next series of updates should start at 8000.
@@ -255,10 +267,8 @@ function comment_schema() {
       )
     ),
     'indexes' => array(
-      'pid' => array('pid'),
-      'nid' => array('nid'),
-      // This index is probably unused.
-      'status' => array('status'),
+      'comment_status_pid' => array('pid', 'status'),
+      'comment_num_new' => array('nid', 'timestamp', 'status'),
     ),
     'primary key' => array('cid'),
     'foreign keys' => array(

modules/comment/comment.module

@@ -1335,7 +1335,7 @@ function comment_num_new($nid, $timestamp = 0) {
     $timestamp = ($timestamp > NODE_NEW_LIMIT ? $timestamp : NODE_NEW_LIMIT);
 
     // Use the timestamp to retrieve the number of new comments.
-    return db_query('SELECT COUNT(c.cid) FROM {node} n INNER JOIN {comment} c ON n.nid = c.nid WHERE n.nid = :nid AND timestamp > :timestamp AND c.status = :status', array(
+    return db_query('SELECT COUNT(cid) FROM {comment} WHERE nid = :nid  AND timestamp > :timestamp AND status = :status', array(
       ':nid' => $nid,
       ':timestamp' => $timestamp,
       ':status' => COMMENT_PUBLISHED,