Although some RDBMS like SQL Server and Oracle provide full-text search capabilities and they have their merits - I would in-general recommend something like Apache SOLR or ElasticSearch.
Full Text Search can be a requirement in many projects.
Apache SOLR and ElasticSearch are more suited if the users are uploading a lot of documents and you need to index them. Storing documents on filestsystem is a better approach than storing them in database as blobs.
Once you have defined your document storage on filesystems, Apache SOLR or ElasticSearch can be configured and they provide a nice REST API for search operations on the documents.
FullText via RDBMS is good option if : you want full text search over the database records and don't have document repository in your application.