--- /checkout/checkout.install
+++ checkout.install
@@ -18,6 +18,14 @@
           KEY (uid)
         ) /*!40100 DEFAULT CHARACTER SET utf8 */"
       );
+      db_query("
+        CREATE TABLE {checkout_lockable} (
+          nid int(10) unsigned NOT NULL default '0',          
+          lockable tinyint(1) unsigned NOT NULL default '0',
+          PRIMARY KEY (nid),
+          KEY (lockable)
+        ) /*!40100 DEFAULT CHARACTER SET utf8 */"
+      );
       break;
     
     case 'pgsql':
@@ -30,6 +38,13 @@
           PRIMARY KEY (nid)
         )"
       );
+      db_query("
+        CREATE TABLE {checkout_lockable} (
+          nid INTEGER NOT NULL DEFAULT 0,
+          lockable SMALLINT NOT NULL DEFAULT 0,
+          PRIMARY KEY (nid)
+        )"
+      );
       db_query("CREATE INDEX {checkout}_uid_idx ON {checkout}(uid)");
       break;
   }