freeform datastore

in my foaf wonderings i came across RDF and triples. there is more to learn there for sure but i think triples are too broad for what i want to use it for.

what i want is a primary key and a hash.

Item #1 make=Sony model=ABC123

Item #2 name=My Toaster weight=12.3

I dont want to define all possible key/value fields nor go through the hastle of modifying SQL tables. I want a hash/dictionary that I can add to at will. I also want to do searches like find items with name=My Toaster or find items with a make and model key.

im thinking a sql table of a unique ID (to make ActiveRecord happy) and a blob field to store a serialized ruby hash. searches would not be able to use the power of the sql engine but i would trade that for the flexability of the hash.