=== modified file 'modules/comment/comment.install'
--- modules/comment/comment.install	2008-01-05 22:45:40 +0000
+++ modules/comment/comment.install	2008-01-12 14:37:47 +0000
@@ -62,7 +62,16 @@ function comment_update_6002() {
  * Add index to parent ID field.
  */
 function comment_update_6003() {
-  $ret[] = update_sql("ALTER TABLE {comments} ADD KEY pid (pid)");
+  $ret = array();
+  switch ($GLOBALS['db_type']) {
+    case 'mysql':
+    case 'mysqli':
+        $ret[] = update_sql("ALTER TABLE {comments} ADD KEY pid(pid)");
+      break;
+    case 'pgsql':
+      $ret[] = update_sql("CREATE INDEX {comments}_pid_idx ON {comments} (pid)");
+      break;
+  }
   return $ret;
 }