I am developing a Rails application that will access a lot of RSS feeds or crawl sites for data (mostly news). It will be something like Google News but with a different approach, so I'll store a lot of news (or news summaries), classify them in different categories and use ranking and recommendation techniques.
Should I go with MySQL?
Is it worthwhile using IBM DB2 purexml to store the doucuments? Also Ruby search implementations (Ferret, Ultrasphinx and others) are not needed If I choose DB2. Is that correct?
What are the advantages of PostreSQL in this?
Does it makes sense to use Couch DB in this scenario?
I'd like to choose the best option but without over-complicating the solution. So I discarded the idea to use two different storage solutions (one for the news documents and other for the rest of the data). I'm also considering only "free" options, so I didn't look at Oracle or MS SQL Server.