1. A computer-implemented method for query optimization in a database management system (DBMS) with memory I/O (input/output) awareness, the method comprising: determining compensated physical I/O (PIO) values indicative of memory I/O operations, including an approximate cache occupancy level, of an executing query in a DBMS; and utilizing the compensated PIO values as feedback to a query optimizer of the DBMS for optimization of future queries.