1.消耗CPU
SELECT a.CPU_TIME, --CPU时间 百万分之一（微秒）
a.OPTIMIZER_MODE,--优化方式
a.EXECUTIONS,--执行次数
a.DISK_READS,--读盘次数
a.SHARABLE_MEM,--占用shared pool的内存多少
a.BUFFER_GETS,--读取缓冲区的次数
a.COMMAND_TYPE,--命令类型(3:select,2:insert;6:update;7delete; 47l/sql程序单元)
a.SQL_TEXT,--Sql语句
a.SHARABLE_MEM,
a.PERSISTENT_MEM,
a.RUNTIME_MEM,
a.PARSE_CALLS,
a.DISK_READS,
a.DIRECT_WRITES,
a.CONCURRENCY_WAIT_TIME,
a.USER_IO_WAIT_TIME
from V$SQLAREA a
WHERE PARSING_SCHEMA_NAME = 'SHODF'--Schema
order by a.CPU_TIME desc


2.最占用资源
select
b.username username,
a.disk_reads reads,
a.executions exec,
a.disk_reads/decode(a.executions,0,1,a.executions) rds_exec_ratio,
a.sql_text Statement
from v$sqlarea a,dba_users b
where a.parsing_user_id=b.user_id and a.disk_reads > 100000
order by a.disk_reads desc;


--用buffer_gets列来替换disk_reads列可以得到占用最多内存的sql语句的相关信


3.列出使用频率最高的5个查询：

select sql_text,executions
from (
select
sql_text,executions, rank() over (order by executions desc) exec_rank
from v$sql)
where exec_rank <=5;
4、消耗磁盘读取最多的sql top5：
select disk_reads,sql_text
from (select sql_text,disk_reads, dense_rank() over (order by disk_reads desc) disk_reads_rank from v$sql)
where disk_reads_rank <=5;
5、找出需要大量缓冲读取（逻辑读）操作的查询：
select buffer_gets,sql_text
from (select sql_text,buffer_gets, dense_rank() over (order by buffer_gets desc) buffer_gets_rank from v$sql)
where buffer_gets_rank<=5;