I confirm the problem reported at the end of this page:
http://wiki.splitbrain.org/plugin:searchindex_manager
Running the indexer from the command line "php5 bin/indexer.php" I get several error message like this:
> Warning: join(): Bad arguments. in /home/dokuwiki/inc/indexer.php on line 56
> Warning: array_keys(): The first argument should be an array in /home/dokuwiki/inc/indexer.php on line 56
The suggested workaround also is good: adding this at line 56 of inc/indexer.php
if (!is_array($links)) { $links = Array($links); }
May be the problem arises only with PHP5? Here version 5.1.6.