Change the Search indexing minimum to 3 characters

[Pugwash]

And my point is that no such limitation exists in PHP, nor can such a setting be configured via php.ini. Granted, having an extension like memcache or xcache enabled might activate some bizarre limitations that I'm not familiar with (although I've used both and never encountered such a thing), but as far as I am aware, there's no such limitation.

As far as I have understood it, he's talking about it being in the PHP source code for phpBB. If you don't have r/w access to the phpBB code, you can't change the minimum search length indexed.