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Comment by collyw | Hacker News Reader

And many many more where it isn't.

My current work, the problem isn't the algorithms that make the thing run slowly, its because the people who wrote it don't know how to use Django efficiently. Lots of loops in the application making database calls each time (our main page is making over 1000 database calls). A bit more thought in the database design, knowing a bit more about how Django's ORM works and you could do all that work in the database in less than 10 calls and make it a lot faster. A couple of extra database indexes in the right places, and a bit of caching and it should run even faster.

Thats the sort of knowledge that is relevant to (most of) our jobs, not big-o.

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This is exactly true. Even at places where the primary money-making IP is a truly novel application of some algorithm, 99.5% of the code are "supporting actors": an API onto that algorithm, plumbing up through layers of middleware, bindings to other languages/frameworks, integration code to shim it through some legacy system, a CRUD interface, etc. My guess is that Google's search code is actually just tiny island of real computer science surrounded by a vast ocean of plumbing, frameworks and middleware, and that when you're hired there, chances are you're not going to be working on that island.

"Lots of loops making database calls each time" improved by "a bit more thought in the design" and "a bit of caching" sounds an awful lot like Big O analysis, and algorithmic optimisation even if it is on top on Django ORM.

Sometimes only. big O cuts all the constants and they are really important in actual software development. A lot of actual work involve improving the speed from a 10N to a 2N, it is a big difference for the costumer, but they are all O(N).

That's not Big O. Big O is asymptotic complexity. Caching, loop optimization, and the like are irrelevant noise to that calculus.

Its not really. Its the same algorithmic complexity (the exception being adding appropriate database indexes), but shifting the where the computation is done.

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