We have a product navigation engine that allow our customers to filter products based on attributes (size, color, etc.). We are implementing an upgrade that allows them to use "multi-select" refinements. Basically they can say "show me all the red, blue, and green products". We want the search engines to crawl just the first page without any refinements. We've set the canonical of the page with refinments on it to the one without any refinements.
From a system resource standpoint I'm not sure I want google crawling all of those refinements links. The links that those refinements generate can be exponentially different based on the the order of the refinements, how many have been selected, etc. It just seems like a waste for google to try and index those pages.
Should I put a no-follow tag on those refinement URL's so that google doesn't even crawl them?