set statistics io reports information about physical and logical I/O and the number of times a table was accessed. set statistics io output follows the query results and provides actual I/O performed by the query.
For each table in a query, including worktables, statistics io reports one line of information with several values for the pages read by the query and one row that reports the total number of writes. If a System Administrator has enabled resource limits, statistics io also includes a line that reports the total actual I/O cost for the query. The following example shows statistics io output for a query with resource limits enabled:
select avg(total_sales) from titles
Table: titles scan count 1, logical reads: (regular=656 apf=0 total=656), physical reads: (regular=444 apf=212 total=656), apf IOs used=212 Total actual I/O cost for this command: 13120. Total writes for this command: 0
The following sections describe the four major components of statistics io output:
Actual I/O cost
Table name and “scan count”