If resource limits are enabled, statistics io prints the “Total actual I/O cost” line. Adaptive Server reports the total actual I/O as a unitless number. The formula for determining the cost of a query is:
Cost = All physical IOs X 25 + All logical IOs X 2 + CPU cost X 0.1
This formula multiplies the “cost” of a logical I/O by the number of logical I/Os and the “cost” of a physical I/O by the number of physical I/Os.
For example:
Table: sysmessages scan count 1, logical reads: (regular=454 apf=0 total=454), physical reads: (regular=441 apf=0 total=441), apf IOs used=10
Total actual I/O cost for this command: 11934
That is: 441*25 + 454*2 + 10*0.1 = 11934
Table 1-1 describes “regular” and “apf” reads.