--查询最慢的sql
select * from (select parsing_user_id,executions,sortscommand_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$process prwhere st.SID=se.SID and st.SID=si.SIDAND SE.PADDR=PR.ADDRAND SE.SID>6AND ST.WAIT_TIME=0AND ST.EVENT NOT LIKE '%SQL%'ORDER BY PHYSICAL_READS DESC;SELECT sql_address FROM V$SESSION SS,V$SQLTEXT TTWHERE SS.SQL_HASH_VALUE=TT.HASH_VALUE AND SID=439;
v$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_$SQLAREA a WHERE PARSING_SCHEMA_NAME = 'CHEA_FILL'--表空间 order by a.CPU_TIME desc
引用：http://jenniferok.iteye.com/blog/700985
从V$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)SQL文本的前 1000个字符SQL_IDVARCHAR2(13)SQL identifier of the parent cursor in the library cacheSHARABLE_MEMNUMBER占用的共享内存大小 (单位： byte)PERSISTENT_MEMNUMBER生命期内的固定内存大小 (单位： byte)RUNTIME_MEMNUMBER执行期内的固定内存大小SORTSNUMBER完成的排序数VERSION_COUNTNUMBERNumber of child cursors that are present in the cache under this parentLOADED_VERSIONSNUMBER显示上下文堆是否载入， 1是 0否OPEN_VERSIONSNUMBER显示子游标是否被锁， 1是 0否USERS_OPENINGNUMBER执行语句的用户数FETCHESNUMBERSQL语句的 fetch数。EXECUTIONSNUMBER自它被载入缓存库后的执行次数END_OF_FETCH_COUNTNUMBERNumber 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_EXECUTINGNUMBER执行语句的用户数LOADSNUMBER对象被载入过的次数FIRST_LOAD_TIMEVARCHAR2(19)初次载入时间INVALIDATIONSNUMBER无效的次数PARSE_CALLSNUMBER解析调用次数DISK_READSNUMBER读磁盘次数DIRECT_WRITESNUMBERSum of the number of direct writes over all child cursorsBUFFER_GETSNUMBER读缓存区次数APPLICATION_WAIT_TIMENUMBERApplication wait timeCONCURRENCY_WAIT_TIMENUMBERConcurrency wait timeCLUSTER_WAIT_TIMENUMBERCluster wait timeUSER_IO_WAIT_TIMENUMBERUser I/O Wait TimePLSQL_EXEC_TIMENUMBERPL/SQL execution timeJAVA_EXEC_TIMENUMBERJava execution timeROWS_PROCESSEDNUMBER解析 SQL语句返回的总列数COMMAND_TYPENUMBER命令类型代号OPTIMIZER_MODEVARCHAR2(25)QL语句的优化器模型PARSING_USER_IDNUMBER第一个解析的用户 IDPARSING_SCHEMA_IDNUMBER第一个解析的计划 IDKEPT_VERSIONSNUMBER指出是否当前子游标被使用 DBMS_SHARED_POOL包标记为常驻内存ADDRESSRAW(4 | 8)当前游标父句柄地址HASH_VALUENUMBERHash value of the parent statement in the library cacheOLD_HASH_VALUENUMBEROld SQL hash valueMODULEVARCHAR2(64)Contains the name of the module that was executing at the time that the SQL statement was first parsed as set by calling DBMS_APPLICATION_INFO .SET_MODULEMODULE_HASHNUMBERHash value of the module that is named in the MODULEcolumnACTIONVARCHAR2(64)Contains the name of the action that was executing at the time that the SQL statement was first parsed as set by calling DBMS_APPLICATION_INFO .SET_ACTIONACTION_HASHNUMBERHash value of the action that is named in the ACTIONcolumnSERIALIZABLE_ABORTSNUMBERNumber of times the transaction fails to serialize, producing ORA-08177 errors, totalled over all the child cursorsCPU_TIMENUMBERCPU time (in microseconds) used by this cursor for parsing/executing/fetchingELAPSED_TIMENUMBERElapsed time (in microseconds) used by this cursor for parsing/executing/fetchingIS_OBSOLETEVARCHAR2(1)Indicates whether the cursor has become obsolete (Y ) or not (N ). This can happen if the number of child cursors is too large.CHILD_LATCHNUMBERChild latch number that is protecting the cursorPROGRAM_IDNUMBER
Program identifie
来源：http://blog.csdn.net/sxhong/article/details/18262663
有很多种方法可以用来找出哪些SQL语句需要优化，但是很久以来，最简单的方法都是分析保存在V$SQL视图中的缓存的SQL信息。通过V$SQL视图，可以确定具有高消耗时间、CUP和IO读取的SQL语句。
1.查看总消耗时间最多的前10条SQL语句select *from (select v.sql_id,v.child_number,v.sql_text,v.elapsed_time,v.cpu_time,v.disk_reads,rank() over(order by v.elapsed_time desc) elapsed_rankfrom v$sql v) awhere elapsed_rank <= 10;
2.查看CPU消耗时间最多的前10条SQL语句select *from (select v.sql_id,v.child_number,v.sql_text,v.elapsed_time,v.cpu_time,v.disk_reads,rank() over(order by v.cpu_time desc) elapsed_rankfrom v$sql v) awhere elapsed_rank <= 10;
3.查看消耗磁盘读取最多的前10条SQL语句select *from (select v.sql_id,v.child_number,v.sql_text,v.elapsed_time,v.cpu_time,v.disk_reads,rank() over(order by v.disk_reads desc) elapsed_rankfrom v$sql v) awhere elapsed_rank <= 10;
select *
from (select sa.SQL_TEXT,
sa.SQL_FULLTEXT,
sa.EXECUTIONS "执行次数",
round(sa.ELAPSED_TIME / 1000000, 2) "总执行时间",
round(sa.ELAPSED_TIME / 1000000 / sa.EXECUTIONS, 2) "平均执行时间",
sa.COMMAND_TYPE,
sa.PARSING_USER_ID "用户ID",
u.username "用户名",
sa.HASH_VALUE
from v$sqlarea sa
left join all_users u
on sa.PARSING_USER_ID = u.user_id
where sa.EXECUTIONS > 0
order by (sa.ELAPSED_TIME / sa.EXECUTIONS) desc)
where rownum <= 50;
select *
from (select s.SQL_TEXT,
s.EXECUTIONS "执行次数",
s.PARSING_USER_ID "用户名",
rank() over(order by EXECUTIONS desc) EXEC_RANK
from v$sql s
left join all_users u
on u.USER_ID = s.PARSING_USER_ID) t
where exec_rank <= 100;
转载于:https://www.cnblogs.com/lidj/p/7125496.html
