+ return array_keys($this->keyTypes());
+ }
+
+ function keyTypes()
+ {
+ return array('canonical' => 'K', 'display' => 'U', 'user_id' => 'U');
+ }
+
+ /**
+ * No sequence keys in this table.
+ */
+ function sequenceKey()
+ {
+ return array(false, false, false);