diff --git a/ctools.install b/ctools.install
index 47f01fb..570a16b 100644
--- a/ctools.install
+++ b/ctools.install
@@ -40,7 +40,23 @@ function ctools_requirements($phase) {
  * Implements hook_schema().
  */
 function ctools_schema() {
-  return ctools_schema_4();
+  return ctools_schema_5();
+}
+
+/**
+ * Version 5 of the CTools schema.
+ */
+function ctools_schema_5() {
+  $schema = ctools_schema_4();
+
+  // Replace the three separate primary keys and add a single one.
+  $schema['ctools_object_cache']['fields']['cid'] = $schema['ctools_object_cache']['fields']['name'];
+  unset($schema['ctools_object_cache']['fields']['sid']);
+  unset($schema['ctools_object_cache']['fields']['name']);
+  unset($schema['ctools_object_cache']['fields']['obj']);
+  $schema['ctools_object_cache']['primary key'] = array('cid');
+
+  return $schema;
 }
 
 /**
@@ -127,12 +143,6 @@ function ctools_schema_1() {
   $schema['ctools_object_cache'] = array(
     'description' => t('A special cache used to store objects that are being edited; it serves to save state in an ordinarily stateless environment.'),
     'fields' => array(
-      'sid' => array(
-        'type' => 'varchar',
-        'length' => '64',
-        'not null' => TRUE,
-        'description' => 'The session ID this cache object belongs to.',
-      ),
       'name' => array(
         'type' => 'varchar',
         'length' => '32',
@@ -277,12 +287,26 @@ function ctools_update_7001() {
 }
 
 /**
- * Increase the length of the ctools_object_cache.name column to 255.
+ * Removed in favor of ctools_update_7003().
  */
 function ctools_update_7002() {
-  db_change_field('ctools_object_cache', 'name', 'name', array(
+}
+
+/**
+ * Combine the three 'ctools_object_cache' key fields into one.
+ */
+function ctools_update_7003() {
+  // Empty the table, drop the primary key, rename the 'name' field to 'cid',
+  // remove the other fields and add the index back again.
+  db_delete('ctools_object_cache')->execute();
+  db_drop_primary_key('ctools_object_cache');
+  db_change_field('ctools_object_cache', 'name', 'cid', array(
     'type' => 'varchar',
     'length' => '255',
     'not null' => TRUE,
+    'description' => 'The primary key of this object.',
   ));
+  db_drop_field('ctools_object_cache', 'sid');
+  db_drop_field('ctools_object_cache', 'obj');
+  db_add_primary_key('ctools_object_cache', array('cid'));
 }
diff --git a/includes/object-cache.inc b/includes/object-cache.inc
index 614c56f..ab48390 100644
--- a/includes/object-cache.inc
+++ b/includes/object-cache.inc
@@ -43,7 +43,12 @@ function ctools_object_cache_get($obj, $name, $skip_cache = FALSE, $sid = NULL)
   }
 
   if (!array_key_exists($key, $cache)) {
-    $data = db_query('SELECT * FROM {ctools_object_cache} WHERE sid = :session_id AND obj = :object AND name = :name', array(':session_id' => $sid, ':object' => $obj, ':name' => $name))
+    $data = db_query('SELECT *
+      FROM {ctools_object_cache}
+      WHERE cid = :cid',
+      array(
+        ':cid' => implode(':', array($sid, $obj, $name)),
+      ))
       ->fetchObject();
     if ($data) {
       $cache[$key] = unserialize($data->data);
@@ -82,9 +87,7 @@ function ctools_object_cache_set($obj, $name, $cache, $sid = NULL) {
 
   db_insert('ctools_object_cache')
     ->fields(array(
-      'sid' => $sid,
-      'obj' => $obj,
-      'name' => $name,
+      'cid' => implode(':', array($sid, $obj, $name)),
       'data' => serialize($cache),
       'updated' => REQUEST_TIME,
     ))
@@ -110,9 +113,7 @@ function ctools_object_cache_clear($obj, $name, $sid = NULL) {
   }
 
   db_delete('ctools_object_cache')
-    ->condition('sid', $sid)
-    ->condition('obj', $obj)
-    ->condition('name', $name)
+    ->condition('cid', implode(':', array($sid, $obj, $name)))
     ->execute();
   // Ensure the static cache is emptied of this obj:name set.
   drupal_static_reset('ctools_object_cache_get');
@@ -178,9 +179,9 @@ function ctools_object_cache_test_objects($obj, $names) {
  *   The name of the object being removed.
  */
 function ctools_object_cache_clear_all($obj, $name) {
+  $cid = implode(':', array('', $obj, $name));
   db_delete('ctools_object_cache')
-    ->condition('obj', $obj)
-    ->condition('name', $name)
+    ->condition('cid', db_like('%' . $cid), 'LIKE')
     ->execute();
   // Ensure the static cache is emptied of this obj:name set.
   $cache = &drupal_static('ctools_object_cache_get', array());