Mine covers tags and other aspects of faceted search as well.
We were able to build a really simple search facility for our marketplace using Postgres in a very short period of time and for cheap. It was incredibly helpful for a small startup short on people and resources.
In this case we wanted to ship the marketplace as quickly as possible (we had some related promotions and partnerships that required it in a specific timeframe) with a tiny team.
Solr/Lucene is the right answer for a full blown solution but it incurs the cost of having to maintain a second service besides your webapp as well as learning and gaining expertise in a second system. All things that can and should be done assuming you see growth, but as quick solution that would work for several months, you can knock out a reasonable search in a couple weeks with tech your app is already using.
Mine covers tags and other aspects of faceted search as well.
We were able to build a really simple search facility for our marketplace using Postgres in a very short period of time and for cheap. It was incredibly helpful for a small startup short on people and resources.