Just pgsql is enough. Even a chache db or sqlite do full text search
I'm not familiar with the various search features of different databases.
Do they offer things like the phonetic search that Solr does?
With Solr you can search a noun for example even if you only know how to say it and not how to spell it.
I've deployed and used it at work for searching specific, well-specified bits of information, but I don't know how well it would work on large chunks of text like articles etc; I assume this is its real purpose and it should fit, but I'm guessing.