Reporting physical and logical I/O statistics

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: