While that's basically true, git grep doesn't scale... With ever-cheaper RAM, ever-faster SSDs, and cloud computing, it could actually make sense, now or soon,

While that's basically true, git grep doesn't scale... With ever-cheaper RAM, ever-faster SSDs, and cloud computing, it could actually make sense, now or soon, to scan through an entire repo, either on "disk" or in RAM. I started building an app that would suck down any GitHub repo by simulating a git clone in the back-end, in the time it took you to type in your query, and hold it in RAM across queries. As a user, I'm sure I would gladly pay however many cents it costs to take up this much RAM when I'm on the search page over the course of a month. Even if a linear scan isn't feasible, regex search at scale is not an unsolved problem, and GitHub has access to world-class engineers. Google Code used trigrams to do regex search with an index (https://swtch.com/~rsc/regexp/regexp4.html https://swtch.com/~rsc/regexp/regexp4.html). Sourcegraph offers regex search.