Google doesn't "rewrite" things in the traditional sense.. they develop new versions of old systems when the old system has reached the limit (or is just grossl

Google doesn't "rewrite" things in the traditional sense.. they develop new versions of old systems when the old system has reached the limit (or is just grossly inefficient). The new systems generally are not at all architecturally similar. I don't think I've ever heard of a rewrite "because the code was messy" or anything other "it can't do X and we need X".