I have an application that will periodically create a large number (10,000+) of hashes (collections of name/value pairs). The hashes may be manipulated a few times, and then deleted.
Is MongoDB an appropriate choice for this? Are there any obviously-better-suited alternatives?
Mongo is a document database and a bit overkill for key/value pairs. It's strength lies in that it can do ad hoc queries in the documents. If you need this, then that's great.
Take a look at tokyocabinet. This is rumored to be a very fast key/value store.
@jmay: there are tons of potential solutions for this stuff: Redis, TokyoCabinet, MongoDB, CouchDB, Cassandra, HBase... just take your pick.
If you consider 10,000+ to be "a large number" then any of these systems will work for you. I'm using Mongo with systems that have four more zeros.
Personally, I like Mongo because it's relatively quick and easy to set up. Check out their quickstart guide and you'll see what I mean.