[chrismcb]

I think it is a horrible assumption to think that Reddit won't grow and will take exactly the same length of time to double the number of unique ids required. But still 64 bits should be plenty for a while. And presumably if it comes closer to using that many they'll have enough time to switch to 128

[aidenn0]

2^63 (assuming signed 64 bit ints) is enough for 10 billion people to post 900 million posts each. Short of faster-than-light travel or the singularity happening, it seems pretty safe.

[masklinn]

Doubling the number of bits does not double the number of values, but squares it.

2^31 seconds is 68 years, a middling human lifetime.

2^63 seconds is 290 billion years.

[masklinn]

(Just so we’re clear, that’s “billion” with a “b”, so 20 times the age of the universe)

[eCa]

> have enough time to switch to 128

It appears that the original developer thought that for 32 bits :)

I say that as someone who inherited a system that allowed for 2^32 session references stored in the db. Lets just say that sessions were created a lot faster than anticipated for the amount of traffic we had.

So one fine Sunday morning in a November a long time ago we ran out.