DBA日常维护SQL整理
database 概况信息检查
# 检查 database 基本信息
select * from v$version;
select name ,open_mode,log_mode from v$database;
select instance_number,instance_name ,status from gv$instance;
show parameter cpu_count
show parameter block_size
select group#,thread#,members,bytes/1024/1024 from gv$log;
show sga
select count(*) from v$controlfile
select count(*) from v$tempfile;
select count(*) from v$datafile;
查看数据文件信息
# 检查表空间数据文件信息
col tablespace_name for a30
select tablespace_name , sum(bytes)/1024/1024 from dba_temp_files group by tablespace_name;
# 检查表空间
SELECT
TABLESPACE_NAME,EXTENT_MANAGEMENT,ALLOCATION_TYPE,SEGMENT_SPACE
_MANAGEMENT FROM DBA_TABLESPACES;
# 检查数据文件状态
select count(*),status from v$datafile group by status;
# 检查表空间使用情况
select
f.tablespace_name,
a.total,
f.free,(a.total-f.free)/1024 "used SIZE(G)"
,round((f.free/a.total)*100) "% Free"
from
(select tablespace_name, sum(bytes/(1024*1024)) total from dba_data_files group by
tablespace_name) a,
(select tablespace_name, round(sum(bytes/(1024*1024))) free from dba_free_space
group by tablespace_name) f
WHERE a.tablespace_name = f.tablespace_name(+)
order by "% Free"
/
# 查询临时 segment 使用情况
COL username FORMAT a10;
COL segtype FORMAT a10;
SELECT username, segtype, extents "Extents Allocated"
,blocks "Blocks Allocated"
FROM v$tempseg_usage;
# 查看数据文件信息 , 若文件较多可以根据需要字段进行排序 输出 top 10
col datafile for a60
SELECT fs.phyrds "Reads", fs.phywrts "Writes"
,fs.avgiotim "Average I/O Time", df.name "Datafile"
FROM v$datafile df, v$filestat fs WHERE df.file# = fs.file#;
# 查看所有数据文件 i/ o 情况 , 若文件太多 , 可以改写 为 top 10 select *( order by xx desc) where
rownum<=10。其中phyrds为物理读的次数极为Reads，phywrts为物理写的次数极为Writes，phyblkrd为物理块读的次数即为br，phyblkwrt为物理写的次数即为bw。readtime为耗费在物理读上的总时间极为RTime，writetim为耗费在物理写上的总时间即为WTime。这两个值只有在参数timed_statistics参数为true时才有效。
COL ts FORMAT a10 HEADING "Tablespace";
COL reads FORMAT 999990;
COL writes FORMAT 999990;
COL br FORMAT 999990 HEADING "BlksRead";
COL bw FORMAT 999990 HEADING "BlksWrite";
COL rtime FORMAT 999990;
COL wtime FORMAT 999990;
SELECT ts.name AS ts, fs.phyrds "Reads", fs.phywrts "Writes"
,fs.phyblkrd AS br, fs.phyblkwrt AS bw
,fs.readtim "RTime", fs.writetim "WTime"
FROM v$tablespace ts, v$datafile df, v$filestat fs
WHERE ts.ts# = df.ts# AND df.file# = fs.file#
UNION
SELECT ts.name AS ts, ts.phyrds "Reads", ts.phywrts "Writes",ts.phyblkrd AS br, ts.phyblkwrt AS bw
,ts.readtim "RTime", ts.writetim "WTime"
FROM v$tablespace ts, v$tempfile tf, v$tempstat ts
WHERE ts.ts# = tf.ts# AND tf.file# = ts.file# ORDER BY 1;
# 获取 top 10 热 segment
set linesize 180
col object_name for a40
select * from
(select
ob.owner, ob.object_name, sum(b.tch) Touchs
from x$bh b , dba_objects ob
where b.obj = ob.data_object_id
and b.ts# > 0
group by ob.owner, ob.object_name
order by sum(tch) desc)
where rownum <=10
# 判断物理读最多的 object
select * from (select owner,object_name,value from v$segment_statistics where
statistic_name='physical reads' order by value desc) where rownum<=10
# 查看热点数据文件 ( 从单块读取时间判断 )
col FILE_NAME for a60
set linesize 180
SELECT t.file_name,
t.tablespace_name,
round(s.singleblkrdtim/s.singleblkrds, 2) AS CS,
s.READTIM,
s.WRITETIM
FROM v$filestat s, dba_data_files t
WHERE s.file# = t.file_id and s.singleblkrds <>0 and rownum<=10 order by cs desc
查看redo
# 检查日志切换频率
select sequence#,to_char(first_time,'yyyymmdd_hh24:mi:ss')
firsttime,round((first_time-lag(first_time) over(order by first_time))*24*60,2) minutes from
v$log_history where first_time > sysdate - 1 order by first_time ,minutes;
# 检查 lgwr i/o 性能 (time_waited/total_waits:表示平均lgwr写入完成时间若>1表示写入过慢 )
select total_waits,time_waited,average_wait,time_waited/total_waits as avg from
v$system_event where event = 'log file parallel write';
# 查询 redo block size
select max(lebsz) from x$kccle;
# 查看 user commit 次数
select to_number(value,99999999999) from v$sysstat where name='user commits';
# 查看系统运行时间
select (sysdate - startup_time)*24*60*60 as seconds from v$instance
# 计算出每秒用户提交次数
select user_commit 次数 / 系统运行时间 from dual;
# 计算出每个事务平均处理多少个 redo block
select value from v$sysstat where name = 'redo blocks written';
select a.redoblocks/b.trancount from (select value redoblocks from v$sysstat where name='redo
blocks written') a ,(select value trancount from v$sysstat where name='user commits') b
sga,pga, 命中率
# sga,pga, 命中率
# 检查 sga
show sga
select * from v$sga;
# 查看buffer cache设置建议
select size_for_estimate, estd_physical_read_factor,
to_char(estd_physical_reads,99999999999999999999999) as"estd_physical_reads" from
v$db_cache_advice where name = 'DEFAULT';
COL pool FORMAT a10;
SELECT (SELECT ROUND(value/1024/1024,0) FROM v$parameter
WHERE name = 'db_cache_size') "Current Cache(Mb)"
,name "Pool", size_for_estimate "Projected Cache(Mb)"
,ROUND(100-estd_physical_read_factor,0) "Cache Hit Ratio%"
FROM v$db_cache_advice
WHERE block_size = (SELECT value FROM v$parameter
WHERE name = 'db_block_size')
ORDER BY 3;
# 查看 pga
show parameter pga
# 查看 cache 池
show parameter cache
# 查看 buffer cache 中 defalut pool 命中率
select name,1-(physical_reads)/(consistent_gets+db_block_gets)
from v$buffer_pool_statistics;
# 检查 shared pool
show parameter shared
# 检查 shared pool 中 library cache
select namespace,pinhitratio from v$librarycache;
# 检查整体命中率 (library cache)
select sum(pinhits)/sum(pins) from v$librarycache;
select sum(pins) "hits",
sum(reloads) "misses",
sum(pins)/(sum(pins)+sum(reloads)) "Hits Ratio"
from v$librarycache;
# 检查 shared pool free space
SELECT * FROM V$SGASTAT
WHERE NAME = 'free memory'
AND POOL = 'shared pool';
# 每个子shared pool 由单独的 shared pool latch保护，查看他们的命中率 shared pool latch，用于shared pool空间回收分配使用的latch
col name format a15
select addr,name,gets,misses,1-misses/gets from v$latch_children where name='shared pool';
# 使用 v$shared_pool_advice 计算不同 shared pool 大小情况下，响应时间， S 单位
SELECT 'Shared Pool' component,
shared_pool_size_for_estimate estd_sp_size,
estd_lc_time_saved_factor parse_time_factor,
CASE
WHEN current_parse_time_elapsed_s + adjustment_s < 0 THEN
0
ELSE
current_parse_time_elapsed_s + adjustment_s
END response_time
FROM (SELECT shared_pool_size_for_estimate,
shared_pool_size_factor,
estd_lc_time_saved_factor,
a.estd_lc_time_saved,
e.VALUE / 100 current_parse_time_elapsed_s,
c.estd_lc_time_saved - a.estd_lc_time_saved adjustment_s FROM v$shared_pool_advice a,
(SELECT * FROM v$sysstat WHERE NAME = 'parse time elapsed') e,
(SELECT estd_lc_time_saved FROM v$shared_pool_advice
WHERE shared_pool_size_factor = 1) c)
/
# 查看 shared pool 中 各种类型的 chunk 的大小数量
SELECT KSMCHCLS CLASS, COUNT(KSMCHCLS) NUM, SUM(KSMCHSIZ) SIZ,
To_char( ((SUM(KSMCHSIZ)/COUNT(KSMCHCLS)/1024)),'999,999.00')||'k' "AVG
SIzE"
FROM X$KSMSP GROUP BY KSMCHCLS;
# 查看是否有库缓冲有关的等待事件
select sid,seq#,event,p1,p1raw,p2,p2raw,p3,p3raw,state from v$session_wait where event like
'library%';
# 查询 sga 中各个 pool 情况
COL name FORMAT a32;
SELECT pool, name, bytes FROM v$sgastat
WHERE pool IS NULL
OR pool != 'shared pool' OR (pool = 'shared pool'
AND (name IN('dictionary cache','enqueue','library
cache','parameters',
'processes','sessions','free memory')))
ORDER BY pool DESC NULLS FIRST, name;
SELECT * FROM V$SGAINFO;
# 查看使用 shard_pool 保留池情况
SELECT request_misses, request_failures, free_space
FROM v$shared_pool_reserved;
Oracle 专门从共享池内置出一块区域来来分配内存保持这些大块。这个保留共享池的默认大小是共享池的5%(_shared_pool_reserved_pct 5 控制 ) oracle 建设置为 10% 。大小通过参数 SHARED_POOL_RESERVED_SIZE 改。它是从共享池中分配，不是直接从 SGA 中分配的，它是共享池的保留部分，专门用于存储大块段#shared pool 中内存大于 _SHARED_POOL_RESERVED_MIN_ALLOC 将放入 shared pool 保留池 , 保留池维护一个单独的 freelist,lru ，并且不会在 lru 列表存recreatable 类型 chunks ，普通 shared pool 的释放与 shared pool 保留池无关。
# 关于设置 SHARED_POOL_RESERVED_SIZE
#1.如果系统出现ora-04031, 发现请求内存都是大于 _SHARED_POOL_RESERVED_MIN_ALLOC (default 10GR2 4400) , 且v$shared_pool_reserved 中有大量 REQUEST_MISSES( 并且可以看下LAST_MISS_SIZE )表示 SHARED_POOL_RESERVED_SIZE 太小了需要大的内存的请求失败 , 那么需要加大SHARED_POOL_RESERVED_SIZE
#2. 如果 ora-04031 请求内存出现在 4100-4400 并造成 shared pool lru 合并 , 老化换出内存 , 可以调小 _SHARED_POOL_RESERVED_MIN_ALLOC 让此部分内存进入shared reserved pool, 相应的加大SHARED_POOL_RESERVED_SIZE
#3. 从 v$shared_pool_reserved 来判断 , 如果 REQUEST_FAILURES>0( 出现过 ora-04031) 且LAST_FAILURE_SIZE( 最后请求内存大小 )>_SHARED_POOL_RESERVED_MIN_ALLOC表示 shared reserved pool 缺少连续内存 , 可以加大 SHARED_POOL_RESERVED_SIZE, 减少 _SHARED_POOL_RESERVED_MIN_ALLOC 少放对象 , 并相对加大 shared_pool_size
# 要是反过来 REQUEST_FAILURES>0( 出现过 ora-04031) 且 LAST_FAILURE_SIZE( 最后请求内存大小)<_SHARED_POOL_RESERVED_MIN_ALLOC, 表示 在 shared pool 中缺少连续内存 , 可以加减少_SHARED_POOL_RESERVED_MIN_ALLOC 多放入一些对象 , 减少 sharedpool 压力 , 适当加大shared_pool_size,SHARED_POOL_RESERVED_SIZE
# 查询还保留在 library cache 中，解析次数和执行次数最多的 sql( 解析 * 执行 )
COL sql_text FORMAT A38;
SELECT * FROM(
SELECT parse_calls*executions "Product", parse_calls
"Parses"
,executions "Execs", sql_text FROM v$sqlarea ORDER BY 1 DESC)
WHERE ROWNUM <= 10;
# 查看 pga
show parameters area_size
# 查看 pga
SELECT * FROM v$pgastat;
# 查看数据库 cache 或 keep 了哪些 object
COL table_name FORMAT A16
COL index_name FORMAT A16
SELECT table_name AS "Table", NULL, buffer_pool, cache FROM
user_tables
WHERE buffer_pool != 'DEFAULT' OR TRIM(cache)='Y'
UNION
SELECT table_name, index_name, NULL, buffer_pool FROM
user_indexes
WHERE buffer_pool != 'DEFAULT'
ORDER BY 1, 2 NULLS FIRST;
# 取消 cache 或 keep(keep pool)
ALTER TABLE XX NOCACHE;
SELECT 'ALTER INDEX '||index_name||' STORAGE(BUFFER_POOL DEFAULT);'
FROM USER_INDEXES WHERE BUFFER_POOL!='DEFAULT';
检查undo
show parameter undo_
# 检查 undo rollback segment 使用情况
select name ,rssize,extents,latch,xacts,writes,gets,waits from v$rollstat a,v$rollname b where
a.usn=b.usn order by waits desc;
select a.redoblocks/b.trancount from (select value redoblocks from v$sysstat where name='redo
blocks written') a ,(select value trancount from v$sysstat where name='user commits') b;
# 计算每秒钟产生的 undoblk 数量
select sum(undoblks)/sum((end_time-begin_time)*24*60*60) from v$undostat;
#Undospace=UR*UPS*blocksize + overload(10%), 计算 undo tablespace 大小
show parameter block_size
show parameter undo_retention
#select undo_retention* 每 秒 产 生 undoblk 数 量 *block_size/1024/1024/1024+
(1+1undo_retention* 每秒产生 undoblk 数量 *block_size/1024/1024/1024*0.1) from dual;
# 查询 undo 具体信息
COL undob FORMAT 99990;
COL trans FORMAT 99990;
COL snapshot2old FORMAT 9999999990;
SELECT undoblks "UndoB", txncount "Trans"
,maxquerylen "LongestQuery", maxconcurrency "MaxConcurrency"
,ssolderrcnt "Snapshot2Old", nospaceerrcnt "FreeSpaceWait"
FROM v$undostat;
# 在内存中排序比率 ( 最优排序 )
SELECT 'Sorts in Memory ' "Ratio"
, ROUND(
(SELECT SUM(value) FROM V$SYSSTAT WHERE name = 'sorts (memory)')
/ (SELECT SUM(value) FROM V$SYSSTAT
WHERE name IN ('sorts (memory)', 'sorts (disk)')) * 100, 5)
||'%' "Percentage"
FROM DUAL;
查看对象
# 检查数据库中无效对象
SELECT owner, object_type,count(object_name) FROM dba_objects WHERE status= 'INVALID'group by owner,object_type;
# 检查是否有禁用约束
SELECT owner, constraint_name, table_name, constraint_type, status
FROM dba_constraints
WHERE status ='DISABLE' and constraint_type='P'
# 检查是否有禁用 trigger
col owner for a10
col taigger_name for a10
cok table_name for a30
col table_name for a30
SELECT owner, trigger_name, table_name, status FROM dba_triggers WHERE status =
'DISABLED';
# 在某个用户下找所有的索引
col column_name for a12
set linesize 180
select user_indexes.table_name, user_indexes.index_name,uniqueness, column_name
from user_ind_columns, user_indexes
where user_ind_columns.index_name = user_indexes.index_name
and user_ind_columns.table_name = user_indexes.table_name
AND user_indexes.table_name='&tb_name'
order by user_indexes.table_type, user_indexes.table_name,
user_indexes.index_name, column_position;
查看当前系统状态
# 检查系统中当前等待事件
col event for a30
select sid,event,p1,p2,p3,p1text,WAIT_TIME,SECONDS_IN_WAIT from v$session_wait where
event not like 'SQL%' and event not like 'rdbms%';
# 查看经常被使用而没有pin在内存中的对象
# 形成生成pin住共享池中当前没有被pin住的对象的sql语句。在执行exec sys.DBMS_SHARED_POOL.keep('JXXXT.IN_GZ_LOGS','P');可能会报出未定义的错误，需要在sqlplus下执行脚本$ORACLE_HOME/rdbms/admin/dbmspool.sql
select 'exec sys.DBMS_SHARED_POOL.keep('||chr(39)||owner||'.'||NAME||chr(39)||','||chr(39)||'P'||chr(39)||');' as sql_to_run
from V$DB_OBJECT_CACHE where TYPE in ('PACKAGE','FUNCTION','PROCEDURE') and loads > 50 and kept='NO' and executions > 50;
# 查看使用了超过10MB内存 而没有pin的对象
SELECT owner,name,sharable_mem,kept FROM V$DB_OBJECT_CACHE
WHERE sharable_mem > 102400 AND kept = 'NO' ORDER BY sharable_mem DESC;
# 查看大的没有被pin住的对象.
set linesize 150
col sz for a10
col name for a100
col keeped for a6
select to_char(sharable_mem / 1024,'999999') sz_in_K, decode(kept, 'yes','yes ','') keeped,
owner||','||name||lpad(' ',29 - (length(owner) + length(name))) || '(' ||type||')'name,
null extra, 0 iscur from v$db_object_cache v where sharable_mem > 1024*1000;
# 查看大的没有被pin住的过程，包和函数
col type for a25
col name for a40
col owner for a25
select owner,name,type,round(sum(sharable_mem/1024),1) sharable_mem_K from v$db_object_cache where kept = 'NO'
and (type = 'PACKAGE' or type = 'FUNCTION' or type = 'PROCEDURE')
group by owner,name,type order by 4;
需要被pin入内存中的对象主要有：常用的较大的存储对象，如standard、diutil包；编译的常用的triggers；sequences。
最好在开机时就将其pin入内存中。这样，既是使用命令alter system flush shared_pool时，也不会讲这些object flush掉。具体pin对象到内存的方法使用DBMS_SHARED_POOL.keep存储过程。可以用unkeep方法解除其pin状态。
db_object_cache和碎片化
碎片化造成在共享池中虽然有许多小的碎片可以使用，但没有足够大的连续空间，这在共享池中是普遍的现象。消除共享池错误的关键就是即将加载对象的大小是否可能会产生问题。一旦知道了这个存在问题的PL/SQL，那么就可以在数据库启动时(这时共享池是完全连续的)就将这个代码固定。这将确保在调用大型包时，它已经在共享池里，而不是在共享池中搜索连续的碎片(在使用系统时，这些碎片可能就不复存在)。可以查询V$DB_OBJECT_CACHE视图来判断PL/SQL是否很大并且还没有被标识为"kept"的标记。今后需要加载这些对象时，可能会产生问题(因为它们的大小和需要占用大量连续的内存)。通过查询V$DB_OBJECT_CACHE表，可以发现那些没有固定，但由于所需空间太大而很有可能导致潜在问题的对象。
# 查询一下回滚段的使用情况，其中USED_UREC为undo记录的使用条目数，USED_UBLK为undo块的使用数目
set linesize 180
SELECT a.sid, a.username, b.xidusn, b.used_urec, b.used_ublk
from v$session a, v$transaction b
WHERE a.saddr = b.ses_addr;
# 查看锁住对象的会话信息，操作系统进程信息
set linesize 180
select object_name,machine,s.sid,s.serial#,p.spid
from v$locked_object l,dba_objects o ,v$session s,v$process p
where l.object_id=o.object_id and l.session_id=s.sid
and s.paddr=p.addr
# 查看被锁的表的被锁时间
set linesize 180
select b.username,b.sid,b.serial#,logon_time
from v$locked_object a,v$session b
where a.session_id = b.sid order by b.logon_time;
# 查看被锁的对象和引起锁的sql
select a.sid,a.username,d.object_name, b.sql_text
from v$session a,v$sql b, v$locked_object c,dba_objects d
where a.sql_hashvalue=b.hash_value
and a.sid = c.session_id
and d.object_id = c.object_id;
# 查看锁定的会话信息
select b.username,b.sid,b.serial#,logon_time
from v$locked_object a,v$session b
where a.session_id = b.sid order by b.logon_time
# 杀死相关会话
alter system kill session 'sid,serial#';
# 如果出现ora-00031错误，则
alter system kill session 'sid,serial#' immediate；
# 亦可先查询该会话相对应的操作系统进程，在操作系统上进行kill
感谢$无为公子的帮助
参考至:http://mlxia./blog/741227
http://blog.csdn.net/soulcq/article/details/5418085
本文原创，转载请注明出处，作者
如有错误，欢迎指正
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