[karmakurtisaani]

How do you fill the array though? Wouldn't filling it with random numbers give you a different hash each time you rebuild the hash function? I can see it being useful for a short-lived data structure, but you wouldn't be able to use it as a shared deterministic hash function?

[ndr]

For in-memory tables you rarely need determinism across instances, let alone runs.

[RhodesianHunter]

Why couldn't you fill it deterministically?

[karmakurtisaani]

I guess that was my question indeed. In the sense of how do you do it in practice? I suppose there are pseudorandom algorithms that can be easily applied.

[cycomanic]

Pseudorandom bit sequences PRBS are deterministic and very easy to implement (just linear feedback shift registers).

Something similar is actually done in communication systems, with scrambling, to prevent long strings of transmitted ones or zeros (which cause issues for some of the hardware components). Essentially you just add or multiply the data with the PRBS sequence. At the receiver you just do the reverse operation.