A full text indexer based on Apache Lucene is available in AEM 6.
If a full-text index is configured, then all queries that have a full-text condition use the full-text index, no matter if there are other conditions that are indexed, and no matter if there is a path restriction.
If no full-text index is configured, then queries with full-text conditions may not work as expected. The query engine has a basic verification in place for full-text conditions, but it does not support all features that Lucene does and it will traverse all nodes if there are no indexed constraints.
Because the index is updated via an asynchronbous background thread, some full-text searches will be unavailable for a small window of time until the background processes are finished.
You can configure a Lucene full-text index, by following the below procedure: