cost of a cpu unit

cost of a cpu unit specifies the cost of a single CPU operation.

Summary Information
Default value	1000
Range of values	1 – 65534
Status	Dynamic
Display level	Comprehensive
Required role	System administrator
Configuration group	Query Tuning

The cost of a serial plan in the optimizer is described by this formula:

Cost = PIO X estimated_pio + LIO X estimated_lio + 100 X CPU/estimated_cpu

Where the default values are:

estimated_pio = 25
estimated_lio = 2
estimated_cpu = 1000

If your SAP ASE has sufficient memory, then all tables exist in memory, and a value of 0 for cost of a physical io is appropriate.

If your CPU is fast enough so the value for cost of a cpu unit is not a issue, use this formula to determine the cost of CPU, which combines 2 LIO and 25 PIO (the default values):

CPU X 100/configuration_value

The default value for configuration_value is 1000.

As you increase the value for cost of a cpu unit, this formula reduces the impact of CPU on cost.