Eu encontrei esta entrada nas configurações:
%FullTextSearch
Full text search (FTS) without database indexing is a very slow operation, and is thus disabled by default.
Before setting Indexed to 1, read docs/full_text_indexing.pod for the full details of FTS on your particular database.
It is possible to enable FTS without database indexing support, simply by setting the Enable key to 1, while leaving Indexed set to 0. This is not generally suggested, as unindexed full-text searching can cause severe performance problems.
Pode ser ativado em RT_SiteConfig.pm