查询oracle比较慢的session和sql

注：本文来源：sxhong   《查询oracle比较慢的session和sql》

---查询最慢的sql

select * from (
select parsing_user_id,executions,sorts
command_type,disk_reads,sql_text from v$sqlarea order by disk_reads desc
)where rownum<10

 ---查询对应session

select SE.SID,SE.SERIAL#,PR.SPID,
SE.USERNAME,SE.STATUS,SE.TERMINAL,
SE.PROGRAM,SE.MODULE,
SE.SQL_ADDRESS,ST.EVENT,
ST.P1TEXT,SI.PHYSICAL_READS,SI.BLOCK_CHANGES from v$session se,v$session_wait st,
v$sess_io si,v$process pr
where st.SID=se.SID and st.SID=si.SID
AND SE.PADDR=PR.ADDR
AND SE.SID>6
AND ST.WAIT_TIME=0
AND ST.EVENT NOT LIKE '%SQL%'
ORDER BY PHYSICAL_READS DESC;
SELECT sql_address FROM V$SESSION SS,V$SQLTEXT TT
WHERE SS.SQL_HASH_VALUE=TT.HASH_VALUE AND SID=439;


--v$sqltext：存储的是完整的SQL,SQL被分割

--v$sqlarea：存储的SQL 和一些相关的信息，比如累计的执行次数，逻辑读，物理读等统计信息（统计）

--v$sql：内存共享SQL区域中已经解析的SQL语句。（即时）



--根据sid查找完整sql语句：

select sql_text from v$sqltext a where a.hash_value = (select sql_hash_value from v$session b where b.sid = '&sid'    )
order by piece asc



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;47:pl/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 SYS.V_$SQLAREA a
 WHERE PARSING_SCHEMA_NAME = 'CHEA_FILL'--表空间
 order by a.CPU_TIME desc





---从V$SQLAREA中查询最占用资源的查询
select b.username username,a.disk_reads reads,
    a.executions exec,a.disk_reads/decode(a.executions,0,1,a.executions) rds_exec_ratio,
    a.sql_text Statement
from  v$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语句的相关信息。

--v$sql：内存共享SQL区域中已经解析的SQL语句。（即时）

--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$sql)
where exec_rank <=5;
--消耗磁盘读取最多的sql top5：
select disk_reads,sql_text
from (select sql_text,disk_reads,
   dense_rank() over
     (order by disk_reads desc) disk_reads_rank
   from v$sql)
where disk_reads_rank <=5;

--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;

v$sqlarea字段定义：http://happyhou.blog.sohu.com/60494432.html

SQL_TEXT	VARCHAR2(1000)	First thousand characters of the SQL text for the current cursor
SQL_ID	VARCHAR2(13)	SQL identifier of the parent cursor in the library cache
SHARABLE_MEM	NUMBER	Amount of shared memory used by a cursor. If multiple child cursors exist, then the sum of all shared memory used by all child cursors.
PERSISTENT_MEM	NUMBER	Fixed amount of memory used for the lifetime of an open cursor. If multiple child cursors exist, the fixed sum of memory used for the lifetime of all the child cursors.
RUNTIME_MEM	NUMBER	Fixed amount of memory required during execution of a cursor. If multiple child cursors exist, the fixed sum of all memory required during execution of all the child cursors.
SORTS	NUMBER	Sum of the number of sorts that were done for all the child cursors
VERSION_COUNT	NUMBER	Number of child cursors that are present in the cache under this parent
LOADED_VERSIONS	NUMBER	Number of child cursors that are present in the cache and have their context heap (KGL heap 6) loaded
OPEN_VERSIONS	NUMBER	The number of child cursors that are currently open under this current parent
USERS_OPENING	NUMBER	Number of users that have any of the child cursors open
FETCHES	NUMBER	Number of fetches associated with the SQL statement
EXECUTIONS	NUMBER	Total number of executions, totalled over all the child cursors
END_OF_FETCH_COUNT	NUMBER	Number of times this cursor was fully executed since the cursor was brought into the library cache. The value of this statistic is not incremented when the cursor is partially executed, either because it failed during the execution or because only the first few rows produced by this cursor are fetched before the cursor is closed or re-executed. By definition, the value of theEND_OF_FETCH_COUNT column should be less or equal to the value of the EXECUTIONS column.
USERS_EXECUTING	NUMBER	Total number of users executing the statement over all child cursors
LOADS	NUMBER	Number of times the object was loaded or reloaded
FIRST_LOAD_TIME	VARCHAR2(19)	Timestamp of the parent creation time
INVALIDATIONS	NUMBER	Total number of invalidations over all the child cursors
PARSE_CALLS	NUMBER	Sum of all parse calls to all the child cursors under this parent
DISK_READS	NUMBER	Sum of the number of disk reads over all child cursors
DIRECT_WRITES	NUMBER	Sum of the number of direct writes over all child cursors
BUFFER_GETS	NUMBER	Sum of buffer gets over all child cursors
APPLICATION_WAIT_TIME	NUMBER	Application wait time
CONCURRENCY_WAIT_TIME	NUMBER	Concurrency wait time
CLUSTER_WAIT_TIME	NUMBER	Cluster wait time
USER_IO_WAIT_TIME	NUMBER	User I/O Wait Time
PLSQL_EXEC_TIME	NUMBER	PL/SQL execution time
JAVA_EXEC_TIME	NUMBER	Java execution time
ROWS_PROCESSED	NUMBER	Total number of rows processed on behalf of this SQL statement
COMMAND_TYPE	NUMBER	Oracle command type definition
OPTIMIZER_MODE	VARCHAR2(25)	Mode under which the SQL statement was executed
PARSING_USER_ID	NUMBER	User ID of the user that has parsed the very first cursor under this parent