Index: modules/system/system.install
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.install,v
retrieving revision 1.107
diff -u -p -r1.107 system.install
--- modules/system/system.install	14 May 2007 16:22:26 -0000	1.107
+++ modules/system/system.install	16 May 2007 00:42:52 -0000
@@ -290,9 +290,11 @@ function system_install() {
         last_comment_timestamp int NOT NULL default '0',
         last_comment_name varchar(60) default NULL,
         last_comment_uid int NOT NULL default '0',
+        last_update_timestamp int NOT NULL default '0',
         comment_count int unsigned NOT NULL default '0',
         PRIMARY KEY (nid),
         KEY node_comment_timestamp (last_comment_timestamp)
+        KEY last_update_timestamp (last_update_timestamp)
       ) /*!40100 DEFAULT CHARACTER SET UTF8 */ ");
 
       db_query("CREATE TABLE {files} (
@@ -785,10 +787,12 @@ function system_install() {
         last_comment_timestamp int NOT NULL default '0',
         last_comment_name varchar(60) default NULL,
         last_comment_uid int NOT NULL default '0',
+        last_update_timestamp int NOT NULL default '0',
         comment_count int_unsigned NOT NULL default '0',
         PRIMARY KEY (nid)
       )");
       db_query("CREATE INDEX {node_comment_statistics}_node_comment_timestamp_idx ON {node_comment_statistics} (last_comment_timestamp)");
+      db_query("CREATE INDEX {node_comment_statistics}_last_update_timestamp_idx ON {node_comment_statistics} (last_update_timestamp)");
 
       db_query("CREATE TABLE {files} (
         fid serial CHECK (fid >= 0),
@@ -3943,6 +3947,69 @@ function system_update_6015() {
 }
 
 /**
+ * Add a last_update_timestamp column to the {node_comment_statistics}
+ * table so that the performance of the tracker query isn't so deadly.
+ */
+function system_update_6016() {
+  $ret = array();
+
+  // Rename the existing table, define a new table with the right
+  // columns, but don't put on the additional indexes until we're done
+  // populating it.
+  switch ($GLOBALS['db_type']) {
+    case 'pgsql':
+      // Drop the old indexes, first.
+      $ret[] = update_sql("DROP INDEX {node_comment_statistics}_node_comment_timestamp_idx");
+      $ret[] = update_sql("DROP INDEX {node_comment_statistics}_last_update_timestamp_idx");
+      $ret[] = update_sql('ALTER TABLE {node_comment_statistics} RENAME TO {node_comment_statistics_tmp}');
+      $ret[] = update_sql("CREATE TABLE {node_comment_statistics} (
+        nid serial CHECK (nid >= 0),
+        last_comment_timestamp int NOT NULL default '0',
+        last_comment_name varchar(60) default NULL,
+        last_comment_uid int NOT NULL default '0',
+        last_update_timestamp int NOT NULL default '0',
+        comment_count int_unsigned NOT NULL default '0',
+        PRIMARY KEY (nid)
+      )");
+      break;
+    case 'mysql':
+    case 'mysqli':
+      $ret[] = update_sql('RENAME TABLE {node_comment_statistics} TO {node_comment_statistics_tmp}');
+      $ret[] = update_sql("CREATE TABLE {node_comment_statistics} (
+        nid int unsigned NOT NULL auto_increment,
+        last_comment_timestamp int NOT NULL default '0',
+        last_comment_name varchar(60) default NULL,
+        last_comment_uid int NOT NULL default '0',
+        last_update_timestamp int NOT NULL default '0',
+        comment_count int unsigned NOT NULL default '0',
+        PRIMARY KEY (nid)
+      ) /*!40100 DEFAULT CHARACTER SET UTF8 */ ");
+      break;
+  }
+
+  // Populate the new table
+  $ret[] = update_sql("INSERT INTO {node_comment_statistics} (nid, last_comment_timestamp, last_comment_name, last_comment_uid, last_update_timestamp, comment_count) SELECT ncs.nid, ncs.last_comment_timestamp, ncs.last_comment_name, ncs.last_comment_uid, GREATEST(ncs.last_comment_timestamp, n.changed), ncs.comment_count FROM {node_comment_statistics_tmp} ncs INNER JOIN {node} n ON ncs.nid = n.nid");
+
+  // Add the indexes
+  switch ($GLOBALS['db_type']) {
+    case 'pgsql':
+      $ret[] = update_sql("CREATE INDEX {node_comment_statistics}_node_comment_timestamp_idx ON {node_comment_statistics} (last_comment_timestamp)");
+      $ret[] = update_sql("CREATE INDEX {node_comment_statistics}_last_update_timestamp_idx ON {node_comment_statistics} (last_update_timestamp)");
+      // While we're in a pgsql-specific block, drop the old indexes, too.
+      break;
+    case 'mysql':
+    case 'mysqli':
+      $ret[] = update_sql("ALTER TABLE {node_comment_statistics} ADD KEY node_comment_timestamp (last_comment_timestamp)");
+      $ret[] = update_sql("ALTER TABLE {node_comment_statistics} ADD KEY last_update_timestamp (last_update_timestamp)");
+      break;
+  }
+  // Finally, drop the tmp table.
+  $ret[] = update_sql("DROP TABLE {node_comment_statistics_tmp}");
+  
+  return $ret;
+}
+
+/**
  * @} End of "defgroup updates-5.x-to-6.x"
  * The next series of updates should start at 7000.
  */
Index: modules/comment/comment.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/comment/comment.module,v
retrieving revision 1.542
diff -u -p -r1.542 comment.module
--- modules/comment/comment.module	14 May 2007 13:43:35 -0000	1.542
+++ modules/comment/comment.module	16 May 2007 00:42:53 -0000
@@ -470,7 +470,7 @@ function comment_nodeapi(&$node, $op, $a
       break;
 
     case 'insert':
-      db_query('INSERT INTO {node_comment_statistics} (nid, last_comment_timestamp, last_comment_name, last_comment_uid, comment_count) VALUES (%d, %d, NULL, %d, 0)', $node->nid, $node->created, $node->uid);
+      db_query('INSERT INTO {node_comment_statistics} (nid, last_comment_timestamp, last_comment_name, last_comment_uid, last_update_timestamp, comment_count) VALUES (%d, %d, NULL, %d, %d, 0)', $node->nid, $node->created, $node->uid, $node->changed);
       break;
 
     case 'delete':
@@ -2008,13 +2008,13 @@ function _comment_update_node_statistics
   // comments exist
   if ($count > 0) {
     $last_reply = db_fetch_object(db_query_range('SELECT cid, name, timestamp, uid FROM {comments} WHERE nid = %d AND status = %d ORDER BY cid DESC', $nid, COMMENT_PUBLISHED, 0, 1));
-    db_query("UPDATE {node_comment_statistics} SET comment_count = %d, last_comment_timestamp = %d, last_comment_name = '%s', last_comment_uid = %d WHERE nid = %d", $count, $last_reply->timestamp, $last_reply->uid ? '' : $last_reply->name, $last_reply->uid, $nid);
+    db_query("UPDATE {node_comment_statistics} SET comment_count = %d, last_comment_timestamp = %d, last_comment_name = '%s', last_comment_uid = %d, last_update_timestamp = %d WHERE nid = %d", $count, $last_reply->timestamp, $last_reply->uid ? '' : $last_reply->name, $last_reply->uid, $last_reply->timestamp, $nid);
   }
 
   // no comments
   else {
-    $node = db_fetch_object(db_query("SELECT uid, created FROM {node} WHERE nid = %d", $nid));
-    db_query("UPDATE {node_comment_statistics} SET comment_count = 0, last_comment_timestamp = %d, last_comment_name = '', last_comment_uid = %d WHERE nid = %d", $node->created, $node->uid, $nid);
+    $node = db_fetch_object(db_query("SELECT uid, created, changed FROM {node} WHERE nid = %d", $nid));
+    db_query("UPDATE {node_comment_statistics} SET comment_count = 0, last_comment_timestamp = %d, last_comment_name = '', last_comment_uid = %d, last_update_timestamp = %d WHERE nid = %d", $node->created, $node->uid, $node->changed, $nid);
   }
 }
 
Index: modules/node/node.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/node/node.module,v
retrieving revision 1.813
diff -u -p -r1.813 node.module
--- modules/node/node.module	15 May 2007 05:43:16 -0000	1.813
+++ modules/node/node.module	16 May 2007 00:42:55 -0000
@@ -703,6 +703,12 @@ function node_save(&$node) {
   db_query($node_query, $node_table_values);
   db_query($revisions_query, $revisions_table_values);
 
+  // Record the last_update time. If this is a new node,
+  // comment_nodeapi() will add the record, so we don't have to.
+  if (!$node->is_new) {
+    db_query("UPDATE {node_comment_statistics} SET last_update_timestamp = %d WHERE nid = %d", $node->changed, $node->nid);
+  }
+
   // Call the node specific callback (if any):
   if ($node->is_new) {
     node_invoke($node, 'insert');
Index: modules/tracker/tracker.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/tracker/tracker.module,v
retrieving revision 1.147
diff -u -p -r1.147 tracker.module
--- modules/tracker/tracker.module	30 Apr 2007 17:03:29 -0000	1.147
+++ modules/tracker/tracker.module	16 May 2007 00:42:57 -0000
@@ -82,16 +82,15 @@ function tracker_page($uid = 0) {
   // Add CSS
   drupal_add_css(drupal_get_path('module', 'tracker') .'/tracker.css', 'module', 'all', FALSE);
 
-  // TODO: These queries are very expensive, see http://drupal.org/node/105639
   if ($uid) {
-    $sql = 'SELECT DISTINCT(n.nid), n.title, n.type, n.changed, n.uid, u.name, GREATEST(n.changed, l.last_comment_timestamp) AS last_updated, l.comment_count FROM {node} n INNER JOIN {node_comment_statistics} l ON n.nid = l.nid INNER JOIN {users} u ON n.uid = u.uid LEFT JOIN {comments} c ON n.nid = c.nid AND (c.status = %d OR c.status IS NULL) WHERE n.status = 1 AND (n.uid = %d OR c.uid = %d) ORDER BY last_updated DESC';
+    $sql = 'SELECT DISTINCT(n.nid), n.title, n.type, n.changed, n.uid, u.name, l.last_update_timestamp AS last_updated, l.comment_count FROM {node} n INNER JOIN {node_comment_statistics} l ON n.nid = l.nid INNER JOIN {users} u ON n.uid = u.uid LEFT JOIN {comments} c ON n.nid = c.nid AND (c.status = %d OR c.status IS NULL) WHERE n.status = 1 AND (n.uid = %d OR c.uid = %d) ORDER BY last_updated DESC';
     $sql = db_rewrite_sql($sql);
     $sql_count = 'SELECT COUNT(DISTINCT(n.nid)) FROM {node} n LEFT JOIN {comments} c ON n.nid = c.nid AND (c.status = %d OR c.status IS NULL) WHERE n.status = 1 AND (n.uid = %d OR c.uid = %d)';
     $sql_count = db_rewrite_sql($sql_count);
     $result = pager_query($sql, 25, 0, $sql_count, COMMENT_PUBLISHED, $uid, $uid);
   }
   else {
-    $sql = 'SELECT DISTINCT(n.nid), n.title, n.type, n.changed, n.uid, u.name, GREATEST(n.changed, l.last_comment_timestamp) AS last_updated, l.comment_count FROM {node} n INNER JOIN {users} u ON n.uid = u.uid INNER JOIN {node_comment_statistics} l ON n.nid = l.nid WHERE n.status = 1 ORDER BY last_updated DESC';
+    $sql = 'SELECT DISTINCT(n.nid), n.title, n.type, n.changed, n.uid, u.name, l.last_update_timestamp AS last_updated, l.comment_count FROM {node} n INNER JOIN {users} u ON n.uid = u.uid INNER JOIN {node_comment_statistics} l ON n.nid = l.nid WHERE n.status = 1 ORDER BY last_updated DESC';
     $sql = db_rewrite_sql($sql);
     $sql_count = 'SELECT COUNT(n.nid) FROM {node} n WHERE n.status = 1';
     $sql_count = db_rewrite_sql($sql_count);