Index: wp-includes/version.php
===================================================================
--- wp-includes/version.php	(revision 4966)
+++ wp-includes/version.php	(working copy)
@@ -3,6 +3,6 @@
 // This holds the version number in a separate file so we can bump it without cluttering the SVN
 
 $wp_version = '2.2-bleeding';
-$wp_db_version = 4860;
+$wp_db_version = 4967;
 
 ?>
Index: wp-admin/upgrade-schema.php
===================================================================
--- wp-admin/upgrade-schema.php	(revision 4966)
+++ wp-admin/upgrade-schema.php	(working copy)
@@ -48,7 +48,8 @@
   link_id bigint(20) NOT NULL default '0',
   category_id bigint(20) NOT NULL default '0',
   PRIMARY KEY  (rel_id),
-  KEY link_id (link_id,category_id)
+  UNIQUE link_id (link_id,category_id),
+  UNIQUE category_id (category_id,link_id)
 ) $charset_collate;
 CREATE TABLE $wpdb->links (
   link_id bigint(20) NOT NULL auto_increment,
@@ -89,7 +90,8 @@
   post_id bigint(20) NOT NULL default '0',
   category_id bigint(20) NOT NULL default '0',
   PRIMARY KEY  (rel_id),
-  KEY post_id (post_id,category_id)
+  UNIQUE post_id (post_id,category_id),
+  UNIQUE category_id (category_id,post_id)
 ) $charset_collate;
 CREATE TABLE $wpdb->postmeta (
   meta_id bigint(20) NOT NULL auto_increment,