Oracle常用的性能诊断语句

--1.阻塞及等待事件信息查询
-- 查询所有会话的状态、等待类型及当前正在执行的SQL脚本
select t.SID, t.SERIAL#, t.Status, t.Action, t.Event, t.BLOCKING_SESSION, t.BLOCKING_SESSION_STATUS
       , t.USERNAME, t.MACHINE, t.PROGRAM, t.sql_exec_start, t.seconds_in_wait
       , NVL(s1.sql_id, s2.sql_id) AS sql_id, NVL(s1.SQL_TEXT, s2.SQL_TEXT) AS sql_text
from v$session t
   left join v$sql s1 on t.SQL_ID = s1.SQL_ID and t.sql_child_number = s1.child_number
   left join v$sql s2 on t.PREV_SQL_ID = s2.SQL_ID and t.prev_child_number = s2.child_number
--where t.PROGRAM = 'w3wp.exe'

-- v1. v$session blocking_session is not null
select gs.INST_ID, gs.SID, gs.BLOCKING_INSTANCE, gs.BLOCKING_SESSION
       , gs.STATUS, gs.EVENT, gs.USERNAME, gs.MACHINE, gs.PROGRAM
from gv$session gs
where gs.BLOCKING_SESSION is not null;

-- v2. v$lock block > 0
select *
from   gv$lock
where  (ID1, ID2, TYPE) in
       (select ID1, ID2, TYPE from gv$lock where block > 0)
order by ID1, block desc;

-- v3. dba_waiters
select * from dba_waiters;

-- v4. v$locked_object
select l.ORACLE_USERNAME, l.OS_USER_NAME, l.LOCKED_MODE, o.OBJECT_NAME
       , s.INST_ID, s.SID, s.STATUS, s.EVENT, s.MACHINE, s.PROGRAM
       , s1.SQL_TEXT, s2.SQL_TEXT
from   gv$locked_object l
  join all_objects o on l.OBJECT_ID = o.OBJECT_ID
  join gv$session s on l.INST_ID = s.INST_ID and l.SESSION_ID = s.SID
  left join gv$sqlarea s1 on s.INST_ID = s1.INST_ID and s.SQL_ID = s1.SQL_ID
  left join gv$sqlarea s2 on s.INST_ID = s2.INST_ID and s.PREV_SQL_ID = s2.SQL_ID

-- 根据sid查到阻塞SQL脚本
select se.INST_ID, se.SID, se.serial#, se.status, se.event, se.BLOCKING_INSTANCE, se.BLOCKING_SESSION
     , se.USERNAME, se.MACHINE, se.PROGRAM, se.sql_exec_start, se.seconds_in_wait
     , tr.xid, tr.start_date, tr.used_ublk, tr.used_urec, NVL(s1.SQL_TEXT, s2.SQL_TEXT) AS sql_text
from gv$session se
   left join gv$transaction tr on se.inst_id = tr.inst_id and se.taddr = tr.addr
   left join gv$sqlarea s1 on se.INST_ID = s1.INST_ID and se.SQL_ID = s1.SQL_ID
   left join gv$sqlarea s2 on se.INST_ID = s2.INST_ID and se.PREV_SQL_ID = s2.SQL_ID
where se.SID in (889, 770);   

-- 未提交的事务、会话
select t.SID, t.SERIAL#, t.STATUS, t.EVENT
     , t.BLOCKING_SESSION, t.BLOCKING_SESSION_STATUS
     , t.MACHINE, t.PROGRAM, t.USERNAME
     , t.TADDR, tr.XID, tr.STATUS, tr.START_DATE, tr.USED_UBLK, tr.USED_UREC
     , nvl(s1.SQL_TEXT, s2.SQL_TEXT) AS sql_text
from  v$session t
   join v$transaction tr on t.TADDR = tr.ADDR
   left join v$sql s1 on t.SQL_ID = s1.SQL_ID and t.SQL_CHILD_NUMBER = s1.CHILD_NUMBER
   left join v$sql s2 on t.PREV_SQL_ID = s2.SQL_ID and t.PREV_CHILD_NUMBER = s2.CHILD_NUMBER;

-- 查询当前系统的等待事件
SELECT event,
       sum(decode(wait_time,0,1,0)) "Curr",
       sum(decode(wait_time,0,0,1)) "Prev",
       count(*)"Total"
FROM v$session_wait
GROUP BY event
ORDER BY count(*) desc;

--2.查找前10条性能差的SQL语句(磁盘读取较大，缺少索引或语句不合理)

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;

-- 查询消耗资源最多的SQL
SELECT sql_text, hash_value, executions, buffer_gets, disk_reads, parse_calls
 FROM V$SQLAREA
WHERE buffer_gets > 10000000 OR disk_reads > 100000
ORDER BY buffer_gets + 100 * disk_reads DESC;

--附
SELECT EXECUTIONS, DISK_READS, BUFFER_GETS 
     , ROUND((BUFFER_GETS-DISK_READS) / BUFFER_GETS, 2) Hit_radio
     , TRUNC(DISK_READS / EXECUTIONS) Reads_per_run
     , SQL_TEXT
FROM  V$SQLAREA 
WHERE EXECUTIONS > 0 AND DISK_READS > 0 and BUFFER_GETS > 0
    AND (BUFFER_GETS-DISK_READS) / BUFFER_GETS < 0.8 
ORDER BY 5 DESC;

-- 查看某条SQL语句的资源消耗　
SELECT HASH_VALUE, BUFFER_GETS, DISK_READS, EXECUTIONS, PARSE_CALLS
  FROM  V$SQLAREA
 WHERE HASH_VALUE = 228801498
   AND ADDRESS = HEXTORAW('CBD8E4B0');

-- 运行时间很长的SQL（session_longops视图显示运行超过6秒的操作。包括备份，恢复，统计信息收集，查询等等）
select b.USERNAME, b.SID, b.SERIAL#, b.START_TIME, b.LAST_UPDATE_TIME
       , round(sofar * 100 / totalwork, 0) || '%' as progress
       , a.sql_text
from v$sqlarea a
     join v$session_longops b on a.SQL_ID = b.SQL_ID
--where b.TIME_REMAINING != 0        -- TIME_REMAINING：预计完成操作的剩余时间(秒)
--  and b.USERNAME = 'sccot'

-- 最近10分钟最消耗CPU的SQL语句：
select sql_text
from (
        select sql_id,count(*) as cn
        from v$active_session_history
        where sample_time > sysdate - 10/24/60
            and session_type <> 'BACKGROUND'
            and SESSION_STATE = 'ON CPU'
        group by sql_id
        order by cn desc
    ) ash, v$sql s
where ash.sql_id=s.sql_id;

-- 最近10分钟最消耗IO的SQL语句：
select sql_text
from (
        select sql_id,count(*) as cn
        from v$active_session_history
        where sample_time > sysdate - 10/24/60
            and session_type <> 'BACKGROUND'
            and WAIT_CLASS='User I/O'
        group by sql_id
        order by cn desc
    ) ash, v$sql s
where ash.sql_id=s.sql_id;

-- 补充1，根据时间找出响应时间较长的SQL：

select t.SQL_TEXT, t.SQL_FULLTEXT, t.ELAPSED_TIME, t.LAST_LOAD_TIME, t.*
   from v$sql t

where t.LAST_LOAD_TIME > to_char(sysdate - 10/(24*60), 'yyyy-mm-dd/hh24:mi:ss') --and t.sql_text like '%LSHSXM%' 
   order by t.ELAPSED_TIME desc;

-- 补充2，查找硬解析严重的SQL：
select max(sql_id), substr(sql_text,0,100), count(1)
from v$sql 
where executions < 10 
group by substr(sql_text,0,100) 
having count(1) > 1000
order by count(1) desc;

--3.统计行数或空间占用较大的表
select   t.table_name, t.num_rows, t.last_analyzed, t.temporary, t.*
from     user_tables t
where t.num_rows > 0
order by t.num_rows desc

-- 普通表数据大小排序
select segment_name,  trunc(bytes/1024/1024)
from user_segments
where segment_type = 'TABLE'
order by bytes desc;

-- 含LOB类型表的数据大小
SELECT A.TABLE_NAME,
       A.COLUMN_NAME,
       trunc(B.BYTES / 1024 / 1024),
       B.SEGMENT_NAME,
       B.SEGMENT_TYPE,
       B.TABLESPACE_NAME,
       B.BLOCKS,
       B.EXTENTS
  FROM USER_LOBS A, USER_SEGMENTS B
WHERE A.SEGMENT_NAME = B.SEGMENT_NAME
ORDER BY B.BYTES DESC;

-- 数据表总的数据大小占用
select  rowSize + nvl(lobSize, 0) dataSize, t1.*, t2.*
from (
          select segment_name,  trunc(bytes/1024/1024) rowSize
          from user_segments
          where segment_type = 'TABLE'
    ) t1 left join (
          SELECT A.TABLE_NAME,
                 A.COLUMN_NAME,
                 trunc(B.BYTES / 1024 / 1024) lobSize,
                 B.SEGMENT_NAME,
                 B.SEGMENT_TYPE,
                 B.TABLESPACE_NAME,
                 B.BLOCKS,
                 B.EXTENTS
            FROM USER_LOBS A, USER_SEGMENTS B
          WHERE A.SEGMENT_NAME = B.SEGMENT_NAME
    ) t2 on t1.segment_name = t2.table_name
order by rowSize + nvl(lobSize, 0) desc

补充，查询该表实际使用的blocks：

SELECT COUNT(DISTINCT DBMS_ROWID.ROWID_BLOCK_NUMBER(rowid) || DBMS_ROWID.ROWID_RELATIVE_FNO(rowid)) AS Used_Blocks
   FROM table_name;

--4.查看Oracle内存参数配置
select *
from   v$parameter t
where  t.NAME in (
              'memory_max_target', 'memory_target', 'sga_max_size', 'sga_target', 'pga_aggregate_target', 'cpu_count'
              , 'db_cache_size', 'shared_pool_size', 'large_pool_size', 'java_pool_size', 'streams_pool_size', 'log_buffer'
              , 'db_2k_cache_size', 'db_4k_cache_size', 'db_8k_cache_size', 'db_16k_cache_size', 'db_32k_cache_size'
       );

-- 查询SGA区的分配细节及使用情况
select t1.pool, t1.reserved_size_mb, t2.used_size_mb, t1.reserved_size_mb - t2.used_size_mb AS unused_size_mb
from (
       select t.POOL, trunc(sum(t.BYTES)/1024/1024) reserved_size_mb
       from v$sgastat t
       where t.POOL is not null
       group by t.POOL
    ) t1
    left join (
      select t.POOL, trunc(sum(t.BYTES)/1024/1024) used_size_mb
      from v$sgastat t
      where t.pool is not null and t.name != 'free memory'
      group by t.POOL
    ) t2 on t1.pool = t2.pool
union all
select t.name, trunc(sum(t.BYTES)/1024/1024) reserved_size_mb, null, null  
from v$sgastat t 
where t.pool is null 
group by t.NAME
order by  2 desc;

-- 查看系统的缓存命中率与软解析率
SELECT 'Cache hit ratio' as name, (1-(physical_reads/(db_block_gets+consistent_gets)))*100 value
FROM v$buffer_pool_statistics
union all
select 'Soft parse ratio', 100-100*(a.value/b.value)
from v$sysstat a, v$sysstat b
Where  a.name='parse count (hard)' and b.name='parse count (total)'; 

--5.查询锁表的语句
select 'kill -9 '||PS.SPID,
    'alter system kill session '''||vs.sid||','||vs.serial#||''';',
    /*       DECODE(V$LOCK.TYPE, 'TM', 'TABLE LOCK', 'TX', 'ROW LOCK', NULL) LOCK_LEVEL,*/
       Decode(VL.LOCKED_MODE,0,'[0] none',
                      1,'[1] null 空',
                      2,'[2] Row-S 行共用(RS)：共用表鎖，sub share ',
                      3,'[3] Row-X 行獨佔(RX)：用於行的修改，sub exclusive ',
                      4,'[4] Share 共用鎖(S)：阻止其他DML操作，share',
                      5,'[5] S/Row-X 共用行獨佔(SRX)：阻止其他事務操作，share/sub exclusive ',
                      6,'[6] exclusive 獨佔(X)：獨立訪問使用，exclusive ',
                      '['||VL.LOCKED_MODE||'] Other Lock') LockMode,
   PS.SPID,OS_USER_NAME,VS.PROGRAM,VS.MACHINE,ORACLE_USERNAME,OBJECT_NAME,vs.LOGON_TIME ,
   Vs.status,vs.MODULE, NVL(currentSql.SQL_TEXT, prevSql.SQL_TEXT) as sql_text
from  V$LOCKED_OBJECT VL
      join DBA_OBJECTS OB on VL.OBJECT_ID = OB.OBJECT_ID
      join V$SESSION VS on VL.SESSION_ID = VS.SID
      join v$process PS on PS.ADDR = VS.PADDR
      --left join v$sql currentSql on vs.SQL_HASH_VALUE = currentSql.HASH_VALUE and vs.SQL_ADDRESS = currentSql.ADDRESS
      --left join v$sql prevSql on vs.PREV_HASH_VALUE = prevSql.HASH_VALUE and vs.PREV_SQL_ADDR = prevSql.ADDRESS
      left join v$sql currentSql on vs.SQL_ID = currentSql.SQL_ID and vs.SQL_Child_Number = currentSql.Child_Number
      left join v$sql prevSql on vs.Prev_SQL_ID = prevSql.Sql_Id and vs.PREV_Child_Number = prevSql.Child_Number
order by vs.logon_time;

--6.产生kill会话的语句
select A.SID,
       B.SPID,
       A.SERIAL#,
       a.lockwait,
       A.USERNAME,
       A.OSUSER,
       a.logon_time,
       a.last_call_et / 3600 LAST_HOUR,
       A.STATUS,
       'orakill ' || sid || ' ' || spid HOST_COMMAND,
       'alter system kill session ''' || A.sid || ',' || A.SERIAL# || '''' SQL_COMMAND
  from v$session A, V$PROCESS B
 where A.PADDR = B.ADDR
   AND SID > 6;

--7.查看IO情况
select
    df.name 文件名,
    fs.phyrds 读次数,
    fs.phywrts 写次数,
    (fs.readtim/decode(fs.phyrds,0,-1,fs.phyrds)) 读时间,
    (fs.writetim/decode(fs.phywrts,0,-1,fs.phywrts)) 写时间
from  v$datafile df,
    v$filestat fs
where df.file#=fs.file#
order by df.name;

--8.查看表空间情况
SELECT UPPER(F.TABLESPACE_NAME) "表空间名",
       D.TOT_GROOTTE_MB "表空间大小(M)",
       D.TOT_GROOTTE_MB - F.TOTAL_BYTES "已使用空间(M)",
       TO_CHAR(ROUND((D.TOT_GROOTTE_MB - F.TOTAL_BYTES) / D.TOT_GROOTTE_MB * 100, 2), '990.99') "使用比",
       F.TOTAL_BYTES "空闲空间(M)",
       F.MAX_BYTES "最大块(M)"
FROM (SELECT TABLESPACE_NAME,
        ROUND(SUM(BYTES) / (1024 * 1024), 2) TOTAL_BYTES,
        ROUND(MAX(BYTES) / (1024 * 1024), 2) MAX_BYTES
        FROM SYS.DBA_FREE_SPACE GROUP BY TABLESPACE_NAME) F,
     (SELECT DD.TABLESPACE_NAME,ROUND(SUM(DD.BYTES) / (1024 * 1024), 2) TOT_GROOTTE_MB
        FROM SYS.DBA_DATA_FILES DD
        GROUP BY DD.TABLESPACE_NAME) D
WHERE D.TABLESPACE_NAME = F.TABLESPACE_NAME
ORDER BY 4 DESC;

--9.根据unix上Top命令看到的PID,查找对应的SQl
SELECT P.pid pid,
       S.sid sid,
       P.spid spid,
       S.username username,
       S.osuser osname,
       P.serial# S_#,
       P.terminal,
       P.program program,
       P.background,
       S.status,
       RTRIM(SUBSTR(a.sql_text, 1, 80)) SQL
  FROM v$process P, v$session S, v$sqlarea A
 WHERE P.addr = s.paddr
   AND S.sql_address = a.address(+)
   AND P.spid LIKE '%CPU最高的进程对应的PID%';

-- 数据库及实例的状态信息
select name, log_mode, open_mode, flashback_on, supplemental_log_data_min, platform_name from v$database;
select instance_number, instance_name, host_name, version, startup_time, status from v$instance;

--清空缓存(共享池和数据缓存)，Command window执行：
alter system flush shared_pool;
alter system flush buffer_cache;

--索引信息查看： 

select t.table_owner, t.index_name, t.blevel, t.leaf_blocks
       , t.last_analyzed, t.distinct_keys, t.num_rows, t.sample_size
from user_indexes t where t.table_name = upper('workitem');

--analyze table 更新统计信息：
analyze table my_table compute statistics; 

analyze index idx_name compute statistics;

--OR
EXEC DBMS_STATS.gather_table_stats(ownname => 'socct', tabname =>'WORKITEM', estimate_percent =>100, cascade =>true, degree =>8, granularity =>'ALL', method_opt => 'for all columns size auto');
/*
参数说明：
一、 estimate_percent ：抽样统计百分比
二、 cascade ：为 false 时 , 只对表进行统计分析；为 true 时 , 同时对表和索引进行统计分析 .
三、 method_opt ：
　 method_opt: 决定 histograms 信息是怎样被统计的 .method_opt 的取值如下 :
　　 for all columns: 统计所有列的 histograms.
　　 for all indexed columns: 统计所有 indexed 列的 histograms.
　　 for all hidden columns: 统计你看不到列的 histograms
　　 for columns <list> SIZE <N> | REPEAT | AUTO | SKEWONLY
　　　　  SIZE ：统计指定列的 histograms.N 的取值范围 [1,254];
  　　　　REPEAT 上次统计过的 histograms;
　　　　  AUTO 由 oracle 决定 N 的大小 ;
四、 degree ：并发性，可调值为， 8/16/24/32...
*/   

--删除数据后，释放数据空间
alter table my_table enable row movement;
alter table my_table shrink space cascade;
alter table my_table disable row movement;

or
alter table table_name move; -- 执行此操作后，需要重建索引

select t.NUM_ROWS, t.TEMPORARY, t.last_analyzed, t.* from user_tables t 
where t.TABLE_NAME = upper('gspauresult_tkk0107');

select t.num_rows, t.distinct_keys, t.sample_size, t.last_analyzed, t.* 
from user_indexes t 
where t.table_name = upper('tkk007');

select t.* from user_ind_columns t 
where t.TABLE_NAME = upper('gspauresult_tkk0107')
order by t.INDEX_NAME, t.COLUMN_POSITION;

select dbms_metadata.get_ddl('TABLE',upper('tkk0107')) from dual;
select dbms_metadata.get_ddl('INDEX',upper('idx_tkk0107')) from dual;
select dbms_metadata.get_ddl('CONSTRAINT',upper('tkk0107')) from dual;
select dbms_metadata.get_ddl('REF_CONSTRAINT',upper('tkk0107')) from dual;
select dbms_metadata.get_ddl('FUNCTION',upper('tkk0107')) from dual;
select dbms_metadata.get_ddl('PACKAGE',upper('tkk0107')) from dual;
select dbms_metadata.get_ddl('VIEW',upper('tkk0107')) from dual;
select dbms_metadata.get_ddl('TABLESPACE',upper('tkk0107')) from dual;
select dbms_metadata.get_ddl('TRIGGER',upper('tkk0107')) from dual;
select dbms_metadata.get_ddl('DB_LINK',upper('tkk0107')) from dual;
select dbms_metadata.get_ddl('MATERIALIZED VIEW',upper('tkk0107')) from dual;

select * from user_tables t order by dbms_random.random;

获取指定SQL在内存中的执行计划：
select sql_id,child_number,sql_text from v$sql where sql_text like 'select count(1) from emp a where a.dept_no =%';
select * from table(DBMS_XPLAN.DISPLAY_CURSOR('sql_id',0)); 

1、PL/SQL Developer 中使用F5
2、explain plan for select count(1) from emp a where a.dept_no=5;
     select * from table(dbms_xplan.display());
3、sqlplus中使用 set autotrace traceonly exp;