pgsql: Improve bit perturbation in TupleHashTableHash.

2018-01-29 Thread Andres Freund
Improve bit perturbation in TupleHashTableHash. The changes in b81b5a96f424531b97cdd1dba97d9d1b9c9d372e did not fully address the issue, because the bit-mixing of the IV into the final hash-key didn't prevent clustering in the input-data survive in the output data. This didn't cause a lot of prob

pgsql: Improve bit perturbation in TupleHashTableHash.

2018-01-29 Thread Andres Freund
Improve bit perturbation in TupleHashTableHash. The changes in b81b5a96f424531b97cdd1dba97d9d1b9c9d372e did not fully address the issue, because the bit-mixing of the IV into the final hash-key didn't prevent clustering in the input-data survive in the output data. This didn't cause a lot of prob