SELECT
A.USERNAME, A.COMMAND, A.STATUS,
A.PROGRAM, A.MACHINE, A.CLIENT_IDENTIFIER,
B.SQL_TEXT,
B.CPU_TIME,
B.SHARABLE_MEM,
ROUND((B.DISK_READS + B.BUFFER_GETS)/B.EXECUTIONS)
AS RESOURCE_COST
FROM
V$SESSION A,
V$SQLSTATS B
WHERE
A.SQL_ID = B.SQL_ID
AND B.EXECUTIONS >0
AND A.WAIT_CLASS <> 'Idle'
ORDER BY
RESOURCE_COST DESC;