SQLProfile: quickie plugin to run DB queries through 'explain' and log ones that trigger filesort or temporary table

plugins/SQLProfile/SQLProfilePlugin.php

@@ -0,0 +1,66 @@
+<?php
+/*
+ * StatusNet - the distributed open-source microblogging tool
+ * Copyright (C) 2010, StatusNet, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+if (!defined('STATUSNET')) {
+    exit(1);
+}
+
+/**
+ * Check DB queries for filesorts and such and log em.
+ *
+ * @package SQLProfilePlugin
+ * @maintainer Brion Vibber <brion@status.net>
+ */
+class SQLProfilePlugin extends Plugin
+{
+    private $recursionGuard = false;
+
+    function onPluginVersion(&$versions)
+    {
+        $versions[] = array('name' => 'SQLProfile',
+                            'version' => STATUSNET_VERSION,
+                            'author' => 'Brion Vibber',
+                            'homepage' => 'http://status.net/wiki/Plugin:SQLProfile',
+                            'rawdescription' =>
+                            _m('Debug tool to watch for poorly indexed DB queries'));
+
+        return true;
+    }
+
+    function onStartDBQuery($obj, $query, &$result)
+    {
+        if (!$this->recursionGuard) {
+            $this->recursionGuard = true;
+            $xobj = clone($obj);
+            $explain = $xobj->query('EXPLAIN ' . $query);
+            $this->recursionGuard = false;
+
+            while ($xobj->fetch()) {
+                $extra = $xobj->Extra;
+                $evil = (strpos($extra, 'Using filesort') !== false) ||
+                        (strpos($extra, 'Using temporary') !== false);
+                if ($evil) {
+                    $xquery = $xobj->sanitizeQuery($query);
+                    common_log(LOG_DEBUG, "$extra | $xquery");
+                }
+            }
+        }
+        return true;
+    }
+}