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$filestat fs WHERE df.file# = fs.file#;
# 查看所有数据文件 i/ o 情况 , 若文件太多 , 可以改写 为 top 10 select *( order by xx desc) where
rownum<=10。其中phyrds为物理读的次数极为Reads，phywrts为物理写的次数极为Writes，phyblkrd为物理块读的次数即为br，phyblkwrt为物理写的次数即为bw。readtime为耗费在物理读上的总时间极为RTime，writetim为耗费在物理写上的总时间即为WTime。这两个值只有在参数timed_statistics参数为true时才有效。
COL ts FORMAT a10 HEADING "Tablespace";
COL reads FORMAT 999990;
COL writes FORMAT 999990;
COL br FORMAT 999990 HEADING "BlksRead";
COL bw FORMAT 999990 HEADING "BlksWrite";
COL rtime FORMAT 999990;
COL wtime FORMAT 999990;
SELECT ts.name AS ts, fs.phyrds "Reads", fs.phywrts "Writes"
,fs.phyblkrd AS br, fs.phyblkwrt AS bwJava 获取指定时间
,fs.readtim "RTime", fs.writetim "WTime"
FROM v$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;