DBA不常用但及时可用的SQL语句集锦（2）

本文（偏于调优）介绍一些DBA日常运维中不常使用，但是遇到特殊情况可以可以及时使用的SQL语句；

注：本文主要针对Oracle 11g版本

Oracle检测死锁的Sql：

SELECT SID, DECODE (BLOCK, 0, 'NO', 'YES') blocker, DECODE (request, 0, 'NO', 'YES') waiter
FROM v$lock
WHERE request > 0 OR BLOCK > 0
ORDER BY BLOCK DESC

SELECT bs.username "Blocking User", bs.username "DB User",

ws.username "Waiting User", bs.SID "SID", ws.SID "WSID",

bs.serial# "Serial#", bs.sql_address "address",

bs.sql_hash_value "Sql hash", bs.program "Blocking App",

ws.program "Waiting App", bs.machine "Blocking Machine",

ws.machine "Waiting Machine", bs.osuser "Blocking OS User",

ws.osuser "Waiting OS User", bs.serial# "Serial#", ws.serial# "WSerial#",

DECODE (wk.TYPE, 'MR', 'Media Recovery', 'RT', 'Redo Thread', 'UN', 'USER Name', 'TX',

'Transaction', 'TM', 'DML', 'UL', 'PL/SQL USER LOCK', 'DX', 'Distributed Xaction',

'CF', 'Control FILE', 'IS', 'Instance State', 'FS', 'FILE SET', 'IR', 'Instance Recovery',

'ST', 'Disk SPACE Transaction', 'TS', 'Temp Segment', 'IV', 'Library Cache Invalidation',

'LS', 'LOG START OR Switch', 'RW', 'ROW Wait', 'SQ', 'Sequence Number', 'TE', 'Extend TABLE',

'TT', 'Temp TABLE', wk.TYPE ) lock_type, DECODE (hk.lmode, 0, 'None', 1, 'NULL', 2,

'ROW-S (SS)', 3, 'ROW-X (SX)', 4, 'SHARE', 5, 'S/ROW-X (SSX)', 6, 'EXCLUSIVE', TO_CHAR (hk.lmode) ) mode_held,

DECODE (wk.request, 0, 'None', 1, 'NULL', 2, 'ROW-S (SS)', 3, 'ROW-X (SX)', 4, 'SHARE', 5, 'S/ROW-X (SSX)', 6,

'EXCLUSIVE', TO_CHAR (wk.request) ) mode_requested, TO_CHAR (hk.id1) lock_id1, TO_CHAR (hk.id2) lock_id2,

DECODE (hk.BLOCK, 0, 'NOT Blocking', /**//* Not blocking any other processes */ 1, 'Blocking',

/**//* This lock blocks other processes */ 2, 'Global', /**//* This lock is global, so we can't tell */ TO_CHAR (hk.BLOCK) ) blocking_others

FROM v$lock hk, v$session bs, v$lock wk, v$session ws

WHERE hk.BLOCK = 1

AND hk.lmode != 0

AND hk.lmode != 1

AND wk.request != 0

AND wk.TYPE(+) = hk.TYPE

AND wk.id1(+) = hk.id1

AND wk.id2(+) = hk.id2

AND hk.SID = bs.SID(+)

AND wk.SID = ws.SID(+)

AND (bs.username IS NOT NULL)

AND (bs.username <> 'SYSTEM')

AND (bs.username <> 'SYS')

ORDER BY 1
/

检查应用系统中无效对象情况（产生无效对象编译脚本情况）：

SELECT 'PROMPT Compile VIEW '||OBJECT_NAME||' ...' || CHR(10)||
'ALTER VIEW '||OBJECT_NAME || ' COMPILE;'||CHR(10)
||'SHOW ERRORS;'||CHR(10) "--COMPILE VIEW "
FROM DBA_OBJECTS
WHERE STATUS <> 'VALID'
AND OBJECT_TYPE = 'VIEW'
ORDER BY OBJECT_NAME


SELECT 'PROMPT Compile TRIGGER '||OBJECT_NAME||' ...'||CHR(10)||
'ALTER TRIGGER '||OBJECT_NAME||' COMPILE;'||CHR(10)
||'SHOW ERRORS;'||CHR(10) "--COMPILE TRIGGER "
FROM DBA_OBJECTS
WHERE STATUS <> 'VALID'
AND OBJECT_TYPE = 'TRIGGER'
ORDER BY OBJECT_NAME
/

查询Oracle隐藏参数：

select x.ksppinm, y.ksppstvl, x.ksppdesc
from x$ksppi x , x$ksppcv y
where x.indx = y.indx
and y.inst_id = userenv('Instance')
and x.inst_id = userenv('Instance')
and x.ksppinm like '\_%' escape '\'
/
或：
SELECT ksppinm, ksppstvl, ksppdesc FROM x$ksppi x, x$ksppcv y WHERE x.indx = y.indx AND ksppinm = '_serial_direct_read'

/

查询数据库SCN的headroom（是指Maximum Reasonable SCN 与当前数据库SCN的差值）是多少：
select

((((

((to_number(to_char(cur_date,'YYYY'))-1988)*12*31*24*60*60) +

((to_number(to_char(cur_date,'MM'))-1)*31*24*60*60) +

(((to_number(to_char(cur_date,'DD'))-1))*24*60*60) +

(to_number(to_char(cur_date,'HH24'))*60*60) +

(to_number(to_char(cur_date,'MI'))*60) +

(to_number(to_char(cur_date,'SS')))

) * (16*1024)) - 12821569053984)

/ (16*1024*60*60*24)

) headroom

from (select to_date('2012-05-30 15:09:57','yyyy-mm-dd hh24:mi:ss') cur_date from dual)
/

查询数据库当前最大的可能SCN“最大合理SCN”：
col for 999,999,999,999,999,999
select

(

(

(

(

(

(

to_char(sysdate,'YYYY')-1988

)*12+

to_char(sysdate,'mm')-1

)*31+to_char(sysdate,'dd')-1

)*24+to_char(sysdate,'hh24')

)*60+to_char(sysdate,'mi')

)*60+to_char(sysdate,'ss')

) * to_number('ffff','XXXXXXXX')/4 scn

from dual

/

根据SCN查询表T更多的历史记录：
Select versions_xid,versions_startscn,versions_endscn,

DECODE(versions_operation,'I','Insert','U','Update','D','Delete', 'Original') "Operation",owner

from t versions between scn minvalue and maxvalue

/

查看正在执行的SQL语句的执行时间和SQL语句的等待事件的信息：
select a.sql_text,b.status,b.last_call_et,b.event

from v$sql a,v$session b

where a.sql_id=b.sql_id and b.sid=41

/
或

select event,p1,p1text,p2,p2text,p3,p3text,wait_time,seconds_in_wait,state
from v$session_wait
where sid=41
/

查看session自运行以来的各种资源消耗统计数据：

select a.sid,b.name,a.value
from v$sesstat a,v$statname b
where a.sid=41
and a.statistic#=b.statistic#
and b.name in ('consistent gets','physical reads','parse count(total)','parse count(hard)')
/

fenng提供了一个sql去判断碎片的程度 如下：
SELECT free_space, avg_free_size,used_space, avg_used_size, request_failures, last_failure_size
FROM v$shared_pool_reserved;
如果：REQUEST_FAILURES > 0
并且 LAST_FAILURE_SIZE < SHARED_POOL_RESERVED_MIN_ALLOC
或者 REQUEST_FAILURES 等于0
并且 LAST_FAILURE_SIZE < SHARED_POOL_RESERVED_MIN_ALLOC
这时候就需要去调整了；



从V$PROCESS中查看PGA总的分配情况：

select spid,program,pga_max_mem max,pga_alloc_mem alloc,pga_used_mem used,pga_freeable_mem free
from v$process
where spid in (select spid from v$process where addr in
(select paddr from v$session where sid in
(select distinct sid from v$mystat)))
/

从v$PROCESS_MEMORY试图中，可以进一步查看PGA各个区域分配的大小：

select p.program,p.spid,pm.category,pm.allocated,pm.used,pm.max_allocated
from v$process p,v$process_memory pm
where p.pid=pm.pid
and p.spid in (select spid from v$process where addr in
(select paddr from v$session where sid in
(select distinct sid from v$mystat)))
/

后续继续补充；

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作者: Seven

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