Re: [SQL] 64-bit hash function, and seeding

2019-03-05 Thread Huon.Wilson
Hi Nicolas, On 6/3/19, 7:48 am, "Nicolas Paris" wrote: Hi Huon Good catch. A 64 bit hash is definitely a useful function. > the birthday paradox implies >50% chance of at least one for tables larger than 77000 rows Do you know how many rows to have 50% chances

Re: [SQL] 64-bit hash function, and seeding

2019-03-05 Thread Nicolas Paris
Hi Huon Good catch. A 64 bit hash is definitely a useful function. > the birthday paradox implies >50% chance of at least one for tables larger > than 77000 rows Do you know how many rows to have 50% chances for a 64 bit hash ? About the seed column, to me there is no need for such an

[SQL] 64-bit hash function, and seeding

2019-03-04 Thread Huon.Wilson
Hi, I’m working on something that requires deterministic randomness, i.e. a row gets the same “random” value no matter the order of the DataFrame. A seeded hash seems to be the perfect way to do this, but the existing hashes have various limitations: - hash: 32-bit output (only 4 billion