I have a mediawiki installation which does not provide search results for words with non Latin characters. Live search works fine, autocompleting on the box, but full text only provides results for Latin based queries.

It is php 5.1.12 and MySQL 5.0.87 mbstring enabled. Multilingual search in other scripts work ok on the server (i.e. SMF/Joomla).

The mediawiki dB was copied by a programmer on an Amazon instance and the search works in that case (the Amazon instance is MySQL: 5.1.37-1ubuntu5 / php 5.1.10).

Any mediawiki experts out there?

Change the database character set to UTF

Thanks! It was a bug caused by Extension:SimpleSecurity

There is a global variable called $wgDBtype that for some reason, the SimpleSecurity extension saw fit to muck with.

Part of the search subsystem depended on this variable being set to "mysql", as it should be. In languages/Language.php, there is the following code:
if ( $wgDBtype != 'mysql' ) {
return $string;
}

$wgDBtype wasn't set to "mysql", so the search string was returned in its raw state. But it needed to be converted! As noted here:

# MySQL fulltext index doesn't grok utf-8, so we
# need to fold cases and convert to hex