数据缓冲区命中率:
(通常>90%，否则请调整sga_target或db_cache_size)

select 100 - ( pr - x) / (cg + dg - x)*100 "db_buffer hit radio(%)" from
(select value pr from v$sysstat where name ='physical reads'),
(select sum(value) x from v$sysstat where name ='physical reads direct' or name ='physical reads direct (lob)'),
(select value cg from v$sysstat where name ='consistent gets'),
(select value dg from v$sysstat where name = 'db block gets')
/

共享池的命中率:
(通常>95%,甚至99%,否则请调整sga_target或share_pool_size)

select sum(pinhits-reloads)/sum(pins)*100 "Share pool hit radio(%)" from v$librarycache
/

数据字典命中率:
select (1 - (sum(getmisses) / sum(gets))) * 100 "Data Dictionary Hit Ratio(%)"
  from v$rowcache;
/

排序区:
(disk与memory的比不能过高，否则调整sort_area_size

select name,value from v$sysstat where name like '%sort%'
/

log_buffer:
(通常redo entries/redo buffer allocation retries > 100否则调整log_buffer):

select name,value from v$sysstat
 where name in('redo entries','redo buffer allocation retries')
/