Optimal DBMS block size regardless of disk type is 4 KB (plus.google.com)

This is a very in-depth analysis of PostgreSql - I would love to see it compared to Oracle, mySql, or SQL server. After reviewing the charts - it made me wonder if the base code had a 4k buffer, so that is why the optimal write block was the same size. One other investigation that is missing is 64 bit vs 32 and different OS