How does Carrot2 clustering scale with respect to the number and length of documents?
The most important characteristic of Carrot2 algorithms to keep in mind is that they perform in-memory clustering. For this reason, as a rule of thumb, Carrot2 should successfully deal with up to a thousand of documents, a few paragraphs each. For algorithms designed to process millions of documents, you may want to check out the Mahout project.
