panel 1: using 32-bit integers is dangerous

Let’s see some examples of how it can go wrong and why it’s almost always better to use 64-bit integers instead!

(32-bit floats are bad too, for similar reasons)

panel 2: 32 bit integers are at most 4 billion

unsigned 32-bit ints go from 0 to 4,294,967,295 (4 billion)

signed 32-bit ints go from -2,147,483,648 to 2,147,483,647

panel 3: times “4 billion” wasn’t enough

Database primary keys: 4 billion records really isn’t that much.

IPv4 addresses: turns out we want more than 4 billion computers on the internet. Oops.

Registers: in the 90s, registers were 32 bits. 4 billion bytes of RAM is 4GB. We need more than that.

Unix timestamps: 2 billion seconds after Jan 1, 1970 is Jan 19, 2038. That’s going to be an exciting day. (look up “2038 problem”!)

panel 4: 64 bits is usually big enough

For example, 2^64 seconds after Jan 1, 1970 is over 100 billion years in the future: well after the death of the sun.

So a 64-bit timestamp is definitely enough space.

panel 5: be wary of using 32-bit integers by accident

Systems that were designed in the 90s often have a 32-bit integer as the default.

For example, in MySQL an INTEGER is 32 bits.