diff --git a/resources/sql/patches/029.cursors.sql b/resources/sql/patches/029.cursors.sql
new file mode 100644
index 0000000000..0512e45e12
--- /dev/null
+++ b/resources/sql/patches/029.cursors.sql
@@ -0,0 +1,13 @@
+ALTER TABLE phabricator_timeline.timeline_event
+  ADD dataID int unsigned;
+
+ALTER TABLE phabricator_timeline.timeline_event
+  ADD UNIQUE KEY (dataID);
+
+UPDATE phabricator_timeline.timeline_event e,
+       phabricator_timeline.timeline_eventdata d
+  SET e.dataID = d.id
+  WHERE d.eventID = e.id;
+
+ALTER TABLE phabricator_timeline.timeline_eventdata
+  DROP eventID;
diff --git a/scripts/sql/upgrade_schema.php b/scripts/sql/upgrade_schema.php
index 3cc2854009..26417647c2 100755
--- a/scripts/sql/upgrade_schema.php
+++ b/scripts/sql/upgrade_schema.php
@@ -1,142 +1,153 @@
 #!/usr/bin/env php
 <?php
 
 /*
  * Copyright 2011 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *   http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 
 $root = dirname(dirname(dirname(__FILE__)));
 require_once $root.'/scripts/__init_script__.php';
 require_once $root.'/scripts/__init_env__.php';
 
+phutil_require_module('phutil', 'console');
+
 const TABLE_NAME = 'schema_version';
 
 if (isset($argv[1]) && !is_numeric($argv[1])) {
   print
     "USAGE: ./update_schema.php [first_patch_version]\n\n".
     "run './update_schema.php 12' to apply all patches starting from ".
     "version 12.\n".
     "run './update_schema.php' to apply all patches that are new since\n".
     "the last time this script was run\n\n";
   exit(0);
 }
 
+echo phutil_console_wrap(
+  "Before running this script, you should take down the Phabricator web ".
+  "interface and stop any running Phabricator daemons.");
+
+if (!phutil_console_confirm('Are you ready to continue?')) {
+  echo "Cancelled.\n";
+  exit(1);
+}
+
 // Use always the version from the commandline if it is defined
 $next_version = isset($argv[1]) ? (int)$argv[1] : null;
 
 // Dummy class needed for creating our database
 class DummyUser extends PhabricatorLiskDAO {
   public function getApplicationName() {
     return 'user';
   }
 }
 
 // Class needed for setting up the actual SQL connection
 class PhabricatorSchemaVersion extends PhabricatorLiskDAO {
   public function getApplicationName() {
     return 'meta_data';
   }
 }
 
 // Connect to 'phabricator_user' db first to create our db
 $conn = id(new DummyUser())->establishConnection('w');
 $create_sql = <<<END
 CREATE DATABASE IF NOT EXISTS `phabricator_meta_data`;
 END;
 queryfx($conn, $create_sql);
 
 // 'phabricator_meta_data' database exists, let's connect to it now
 $conn = id(new PhabricatorSchemaVersion())->establishConnection('w');
 $create_sql = <<<END
 CREATE TABLE IF NOT EXISTS phabricator_meta_data.`schema_version` (
   `version` INTEGER not null
 );
 END;
 queryfx($conn, $create_sql);
 
 // Get the version only if commandline argument wasn't given
 if ($next_version === null) {
   $version = queryfx_one(
     $conn,
     'SELECT * FROM %T',
     TABLE_NAME);
 
   if (!$version) {
     print "*** No version information in the database ***\n";
     print "*** Give the first patch version which to  ***\n";
     print "*** apply as the command line argument     ***\n";
     exit(-1);
   }
 
   $next_version = $version['version'] + 1;
 }
 
 // Find the patch files
 $patches_dir = $root.'/resources/sql/patches/';
 $finder = id(new FileFinder($patches_dir))
   ->withSuffix('sql');
 $results = $finder->find();
 
 $patches = array();
 foreach ($results as $r) {
   $matches = array();
   if (preg_match('/(\d+)\..*\.sql$/', $r, $matches)) {
     $patches[] = array('version' => (int)$matches[1],
                        'file' => $r);
   } else {
     print
       "*** WARNING : File {$r} does not follow the normal naming ".
       "convention. ***\n";
   }
 }
 
 // Files are in some 'random' order returned by the operating system
 // We need to apply them in proper order
 $patches = isort($patches, 'version');
 
 $patch_applied = false;
 foreach ($patches as $patch) {
   if ($patch['version'] < $next_version) {
     continue;
   }
 
   print "Applying patch {$patch['file']}\n";
 
   $path = Filesystem::resolvePath($patches_dir.$patch['file']);
 
   $user = PhabricatorEnv::getEnvConfig('mysql.user');
   $pass = PhabricatorEnv::getEnvConfig('mysql.pass');
   $host = PhabricatorEnv::getEnvConfig('mysql.host');
 
   list($stdout, $stderr) = execx(
     "mysql --user=%s --password=%s --host=%s < %s",
     $user, $pass, $host, $path);
 
   if ($stderr) {
     print $stderr;
     exit(-1);
   }
 
   // Patch was successful, update the db with the latest applied patch version
   // 'DELETE' and 'INSERT' instead of update, because the table might be empty
   queryfx($conn, 'DELETE FROM %T', TABLE_NAME);
   queryfx($conn, 'INSERT INTO %T values (%d)', TABLE_NAME, $patch['version']);
 
   $patch_applied = true;
 }
 
 if (!$patch_applied) {
   print "Your database is already up-to-date\n";
 }
diff --git a/src/applications/daemon/controller/timelineevent/PhabricatorDaemonTimelineEventController.php b/src/applications/daemon/controller/timelineevent/PhabricatorDaemonTimelineEventController.php
index 126d37a1b4..a1499d141d 100644
--- a/src/applications/daemon/controller/timelineevent/PhabricatorDaemonTimelineEventController.php
+++ b/src/applications/daemon/controller/timelineevent/PhabricatorDaemonTimelineEventController.php
@@ -1,79 +1,80 @@
 <?php
 
 /*
  * Copyright 2011 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *   http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 
 class PhabricatorDaemonTimelineEventController
   extends PhabricatorDaemonController {
 
   private $id;
 
   public function willProcessRequest(array $data) {
     $this->id = $data['id'];
   }
 
   public function processRequest() {
     $event = id(new PhabricatorTimelineEvent('NULL'))->load($this->id);
     if (!$event) {
       return new Aphront404Response();
     }
 
     $request = $this->getRequest();
     $user = $request->getUser();
 
-    $data = id(new PhabricatorTimelineEventData())->loadOneWhere(
-      'eventID = %d',
-      $event->getID());
+    if ($event->getDataID()) {
+      $data = id(new PhabricatorTimelineEventData())->load(
+        $event->getDataID());
+    }
 
     if ($data) {
       $data = json_encode($data->getEventData());
     } else {
       $data = 'null';
     }
 
     $form = new AphrontFormView();
     $form
       ->setUser($user)
       ->appendChild(
         id(new AphrontFormStaticControl())
           ->setLabel('ID')
           ->setValue($event->getID()))
       ->appendChild(
         id(new AphrontFormStaticControl())
           ->setLabel('Type')
           ->setValue($event->getType()))
       ->appendChild(
         id(new AphrontFormTextAreaControl())
           ->setDisabled(true)
           ->setLabel('Data')
           ->setValue($data))
       ->appendChild(
         id(new AphrontFormSubmitControl())
           ->addCancelButton('/daemon/timeline/'));
 
     $panel = new AphrontPanelView();
     $panel->setHeader('Event');
     $panel->setWidth(AphrontPanelView::WIDTH_FORM);
     $panel->appendChild($form);
 
     return $this->buildStandardPageResponse(
       $panel,
       array(
         'title' => 'Timeline Event',
       ));
   }
 
 }
diff --git a/src/infrastructure/daemon/timeline/cursor/iterator/PhabricatorTimelineIterator.php b/src/infrastructure/daemon/timeline/cursor/iterator/PhabricatorTimelineIterator.php
index 1aadedeefc..0fc1b5bcd4 100644
--- a/src/infrastructure/daemon/timeline/cursor/iterator/PhabricatorTimelineIterator.php
+++ b/src/infrastructure/daemon/timeline/cursor/iterator/PhabricatorTimelineIterator.php
@@ -1,116 +1,116 @@
 <?php
 
 /*
  * Copyright 2011 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *   http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 
 class PhabricatorTimelineIterator implements Iterator {
 
   protected $cursorName;
   protected $eventTypes;
 
   protected $cursor;
 
   protected $index  = -1;
   protected $events = array();
 
   const LOAD_CHUNK_SIZE = 128;
 
   public function __construct($cursor_name, array $event_types) {
     $this->cursorName = $cursor_name;
     $this->eventTypes = $event_types;
   }
 
   protected function loadEvents() {
     if (!$this->cursor) {
       $this->cursor = id(new PhabricatorTimelineCursor())->loadOneWhere(
         'name = %s',
         $this->cursorName);
       if (!$this->cursor) {
         $cursor = new PhabricatorTimelineCursor();
         $cursor->setName($this->cursorName);
         $cursor->setPosition(0);
         $cursor->save();
 
         $this->cursor = $cursor;
       }
     }
 
     $event = new PhabricatorTimelineEvent('NULL');
     $event_data = new PhabricatorTimelineEventData();
     $raw_data = queryfx_all(
       $event->establishConnection('r'),
       'SELECT event.*, event_data.eventData eventData
         FROM %T event
-        LEFT JOIN %T event_data ON event_data.eventID = event.id
+        LEFT JOIN %T event_data ON event_data.id = event.dataID
         WHERE event.id > %d AND event.type in (%Ls)
         ORDER BY event.id ASC LIMIT %d',
       $event->getTableName(),
       $event_data->getTableName(),
       $this->cursor->getPosition(),
       $this->eventTypes,
       self::LOAD_CHUNK_SIZE);
 
     $events = $event->loadAllFromArray($raw_data);
     $events = mpull($events, null, 'getID');
     $raw_data = ipull($raw_data, 'eventData', 'id');
     foreach ($raw_data as $id => $data) {
       if ($data) {
         $decoded = json_decode($data, true);
         $events[$id]->setData($decoded);
       }
     }
 
     $this->events = $events;
 
     if ($this->events) {
       $this->events = array_values($this->events);
       $this->index = 0;
     } else {
       $this->cursor = null;
     }
   }
 
   public function current() {
     return $this->events[$this->index];
   }
 
   public function key() {
     return $this->events[$this->index]->getID();
   }
 
   public function next() {
     if ($this->valid()) {
       $this->cursor->setPosition($this->key());
       $this->cursor->save();
     }
 
     $this->index++;
     if (!$this->valid()) {
       $this->loadEvents();
     }
   }
 
   public function valid() {
     return isset($this->events[$this->index]);
   }
 
   public function rewind() {
     if (!$this->valid()) {
       $this->loadEvents();
     }
   }
 
 }
diff --git a/src/infrastructure/daemon/timeline/storage/event/PhabricatorTimelineEvent.php b/src/infrastructure/daemon/timeline/storage/event/PhabricatorTimelineEvent.php
index 966fa4e94d..8ff507624a 100644
--- a/src/infrastructure/daemon/timeline/storage/event/PhabricatorTimelineEvent.php
+++ b/src/infrastructure/daemon/timeline/storage/event/PhabricatorTimelineEvent.php
@@ -1,65 +1,71 @@
 <?php
 
 /*
  * Copyright 2011 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *   http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 
 class PhabricatorTimelineEvent extends PhabricatorTimelineDAO {
 
   protected $type;
+  protected $dataID;
+
   private $data;
 
   public function __construct($type, $data = null) {
     parent::__construct();
 
     if (strlen($type) !== 4) {
       throw new Exception("Event types must be exactly 4 characters long.");
     }
 
     $this->type = $type;
     $this->data = $data;
   }
 
   public function getConfiguration() {
     return array(
       self::CONFIG_TIMESTAMPS => false,
     ) + parent::getConfiguration();
   }
 
   public function recordEvent() {
     if ($this->getID()) {
       throw new Exception("Event has already been recorded!");
     }
 
-    $this->save();
-
+    // Save the data first and point to it from the event to avoid a race
+    // condition where we insert the event before the data and a consumer reads
+    // it immediately.
     if ($this->data !== null) {
       $data = new PhabricatorTimelineEventData();
-      $data->setEventID($this->getID());
       $data->setEventData($this->data);
       $data->save();
+
+      $this->setDataID($data->getID());
     }
+
+    $this->save();
   }
 
   public function setData($data) {
     $this->data = $data;
     return $this;
   }
 
   public function getData() {
     return $this->data;
   }
 
 }
diff --git a/src/infrastructure/daemon/timeline/storage/eventdata/PhabricatorTimelineEventData.php b/src/infrastructure/daemon/timeline/storage/eventdata/PhabricatorTimelineEventData.php
index 0bcf9d3035..407d4e1ece 100644
--- a/src/infrastructure/daemon/timeline/storage/eventdata/PhabricatorTimelineEventData.php
+++ b/src/infrastructure/daemon/timeline/storage/eventdata/PhabricatorTimelineEventData.php
@@ -1,33 +1,32 @@
 <?php
 
 /*
  * Copyright 2011 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *   http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 
 class PhabricatorTimelineEventData extends PhabricatorTimelineDAO {
 
-  protected $eventID;
   protected $eventData;
 
   public function getConfiguration() {
     return array(
       self::CONFIG_SERIALIZATION => array(
         'eventData' => self::SERIALIZATION_JSON,
       ),
       self::CONFIG_TIMESTAMPS => false,
     ) + parent::getConfiguration();
   }
 
 }