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Comment by tikhonj | Hacker News Reader

There's a rough rule of thumb that you should expect to redesign your system to handle each order of magnitude increase in scale, and I figure it applies here too—gracefully handling that size of repo would require substantial engineering work, and they have plenty of time to handle it before human-oriented open source repos get even close to the current limit.

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I'm not sure redesigns were necessary between going 1 to 10, from 10 to 100, from 100 to 1000, from 1000 to 10'000, from 10'000 to 100'000, or from 100'000 to 1000'000 which we're now at. It sounds like a sensible engineering rule, but I'm not sure it translates to software, or at least not in this case. I don't know of any design changes made to Git since it was first created, there's no v1 and v2 repositories for example.

> there's no v1 and v2 repositories for example

We wouldn’t know. GitHub is probably running something very different to normal local git including optimizations for performance and cost.

They must only ensure API/protocol compatibility and could have already replaced everything else many times over.

It depends on how quickly you pass through each order of magnitude milestone. I remember reading about how MySpace grew something like five orders of magnitude in less than a year, and no matter how scalable your architecture is you're going to hit a point during that where you need to rearchitect your whole system.

Slower growth allows for forward planning and incremental architectural changes.

> There's a rough rule of thumb that you should expect to redesign your system to handle each order of magnitude increase in scale

I rather know the rule: by good engineering, you can modify a system to handle a one magnitude increase with respect what it was designed for. As soon as a two magnitude increase can occur, you better redesign the system.

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