- Patch #690746 by Damien Tournoud, Stevel: avoid table descriptions from disappearing.

modules/system/system.install

@@ -2454,9 +2454,15 @@ function system_update_7054() {
   // Update: update_fix_d7_requirements() installs this version for cache_path
   // already, so we don't include it in this particular update. It should be
   // included in later updates though.
-  $cache_tables = array('cache', 'cache_form', 'cache_menu', 'cache_page');
+  $cache_tables = array(
+    'cache' => 'Generic cache table for caching things not separated out into their own tables. Contributed modules may also use this to store cached items.',
+    'cache_form' => 'Cache table for the form system to store recently built forms and their storage data, to be used in subsequent page requests.',
+    'cache_page' => 'Cache table used to store compressed pages for anonymous users, if page caching is enabled.',
+    'cache_menu' => 'Cache table for the menu system to store router information as well as generated link trees for various menu/page/user combinations.',
+  );
   $schema = system_schema_cache_7054();
   foreach ($cache_tables as $table => $description) {
+    $schema['description'] = $description;
     db_drop_table($table);
     db_create_table($table, $schema);
   }