Performance issue with generation of random unique numbers

Question

I have a situation where by I need to create tens of thousands of unique numbers. However these numbers must be 9 digits and cannot contain any 0\'s. My current approach is

Answer 1

This suggestion may or may not be popular.... it depends on people's perspective. Because you haven't been too specific about what you need them for, how often, or the exact number, I will suggest a brute force approach.

I would generate a hundred thousand numbers - shouldn't take very long at all, maybe a few seconds? Then use Parallel LINQ to do a Distinct() on them to eliminate duplicates. Then use another PLINQ query to run a regex against the remainder to eliminate any with zeroes in them. Then take the top x thousand. (PLINQ is brilliant for ripping through large tasks like this). If needed, rinse and repeat until you have enough for your needs.

On a decent machine it will just about take you longer to write this simple function than it will take to run it. I would also query why you have 400K entries to test when you state you actually need "tens of thousands"?