optimizer_index_cost_adj.sql

col c1 heading ‘Average Waits for|Full Scan Read I/O’ format 9999.999
col c2 heading ‘Average Waits for|Index Read I/O’ format 9999.999
col c3 heading ‘Percent of| I/O Waits|for Full Scans’ format 9.99
col c4 heading ‘Percent of| I/O Waits|for Index Scans’ format 9.99
col c5 heading ‘Starting|Value|for|optimizer|index|cost|adj’ format 999

select
a.average_wait c1,
b.average_wait c2,
a.total_waits /(a.total_waits + b.total_waits) c3,
b.total_waits /(a.total_waits + b.total_waits) c4,
(b.average_wait / a.average_wait)*100 c5
from
v$system_event a,
v$system_event b
where
a.event = ‘db file scattered read’
and
b.event = ‘db file sequential read’
;

source : https://www.techrepublic.com/article/database-optimization-tweaking-oracle-sql-performance-parameters/#

https://www.techrepublic.com/html/tr/sidebars/5138236-0.html