Oracle日常效能檢視

建立時間： 2014-4-10 11:39 修改時間： 2015-4-8 13:48 來源： http://blog.chinaunix.net/uid-20784775-id-373968.html

1.判斷回滾段競爭的SQL語句：（當Ratio大於2時存在回滾段競爭，需要增加更多的回滾段）
select rn.name, rs.GETS, rs.WAITS, (rs.WAITS / rs.GETS) * 100 ratio
from v$rollstat rs, v$rollname rn
where rs.USN = rn.usn

2.判斷恢復日誌競爭的SQL語句：（immediate_contention或wait_contention的值大於1時存在競爭）
select name,
(t.IMMEDIATE_MISSES /
decode((t.IMMEDIATE_GETS t.IMMEDIATE_MISSES),
0,
-1,
(t.IMMEDIATE_GETS t.IMMEDIATE_MISSES))) * 100 immediate_contention,
(t.MISSES / decode((t.GETS t.MISSES), 0, -1, (t.GETS t.MISSES))) * 100 wait_contention
from v$latch t
where name in ('redo copy', 'redo allocation')

3.判斷表空間碎片：（如果最大空閒空間佔總空間很大比例則可能不存在碎片，如果比例較小，且有許多空閒空間，則可能碎片很多）
select t.tablespace_name,
sum(t.bytes),
max(t.bytes),
count(*),
max(t.bytes) / sum(t.bytes) radio
from dba_free_space t
group by t.tablespace_name
order by t.tablespace_name

4. 確定命中排序域的次數：

select t.NAME, t.VALUE from v$sysstat t where t.NAME like 'sort%'

5.檢視當前SGA值：
select * from v$sga

6.確定高速緩衝區命中率：（如果命中率低於70％，則應該加大init.ora引數中的DB_BLOCK_BUFFER的值）
select 1 - sum(decode(name, 'physical reads', value, 0)) /
(sum(decode(name, 'db block gets', value, 0))
sum(decode(name, 'consistent gets', value, 0))) hit_ratio
from v$sysstat t
where name in ('physical reads', 'db block gets', 'consistent gets')

7.確定共享池中的命中率：（如果ratio1大於1時，需要加大共享池，如果ratio2大於10％時，需要加大共享池SHARED_POOL_SIZE）
select sum(pins) pins,
sum(reloads) reloads,
(sum(reloads) / sum(pins)) * 100 ratio1
from v$librarycache

select sum(gets) gets,
sum(getmisses) getmisses,
(sum(getmisses) / sum(gets)) * 100 ratio2
from v$rowcache

8.查詢INIT.ORA引數：
select * from v$parameter

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Oracle效能引數檢視（轉）
0、資料庫引數屬性
col PROPERTY_NAME format a25
col PROPERTY_VALUE format a30
col DESCRIPTION format a100
select * from database_properties;
select * from v$version;

1、求當前會話的SID，SERIAL#
SELECT Sid, Serial# FROM V$session
WHERE Audsid = Sys_Context('USERENV', 'SESSIONID');

2、查詢session的OS程式ID
SELECT p.Spid "OS Thread", b.NAME "Name-User", s.Program, s.Sid, s.Serial#,s.Osuser, s.Machine
FROM V$process p, V$session s, V$bgprocess b
WHERE p.Addr = s.Paddr
AND p.Addr = b.Paddr And (s.sid=&1 or p.spid=&1)
UNION ALL
SELECT p.Spid "OS Thread", s.Username "Name-User", s.Program, s.Sid,s.Serial#, s.Osuser, s.Machine
FROM V$process p, V$session s
WHERE p.Addr = s.Paddr
And (s.sid=&1 or p.spid=&1)
AND s.Username IS NOT NULL;

3、根據sid檢視對應連線正在執行的sql
SELECT /* PUSH_SUBQ */ Command_Type, Sql_Text, Sharable_Mem, Persistent_Mem, Runtime_Mem, Sorts,
Version_Count, Loaded_Versions, Open_Versions, Users_Opening, Executions,
Users_Executing, Loads, First_Load_Time, Invalidations, Parse_Calls,
Disk_Reads, Buffer_Gets, Rows_Processed, SYSDATE Start_Time,
SYSDATE Finish_Time, '>' || Address Sql_Address, 'N' Status
FROM V$sqlarea WHERE Address = (SELECT Sql_Address
FROM V$session WHERE Sid = &sid );

4、查詢object為哪些程式所用
SELECT p.Spid, s.Sid, s.Serial# Serial_Num, s.Username User_Name,
a.TYPE Object_Type, s.Osuser Os_User_Name, a.Owner,
a.OBJECT Object_Name,
Decode(Sign(48 - Command), 1, To_Char(Command), 'Action Code #' || To_Char(Command)) Action,
p.Program Oracle_Process, s.Terminal Terminal, s.Program Program,
s.Status Session_Status
FROM V$session s, V$access a, V$process p
WHERE s.Paddr = p.Addr
AND s.TYPE = 'USER'
AND a.Sid = s.Sid
AND a.OBJECT = '&obj'
ORDER BY s.Username, s.Osuser

5、檢視有哪些使用者連線
SELECT s.Osuser Os_User_Name,Decode(Sign(48 - Command),1,To_Char(Command),
'Action Code #' || To_Char(Command)) Action,
p.Program Oracle_Process, Status Session_Status, s.Terminal Terminal,
s.Program Program, s.Username User_Name,
s.Fixed_Table_Sequence Activity_Meter, '' Query, 0 Memory,
0 Max_Memory, 0 Cpu_Usage, s.Sid, s.Serial# Serial_Num
FROM V$session s, V$process p
WHERE s.Paddr = p.Addr
AND s.TYPE = 'USER'
ORDER BY s.Username, s.Osuser

6、根據v.sid檢視對應連線的資源佔用等情況
SELECT n.NAME, v.VALUE, n.CLASS, n.Statistic# FROM V$statname n, V$sesstat v
WHERE v.Sid = &sid
AND v.Statistic# = n.Statistic#
ORDER BY n.CLASS, n.Statistic#

7、查詢耗資源的程式（top session）
SELECT s.Schemaname Schema_Name,Decode(Sign(48 - Command),
1, To_Char(Command), 'Action Code #' || To_Char(Command)) Action,Status Session_Status, s.Osuser Os_User_Name, s.Sid, p.Spid,s.Serial# Serial_Num, Nvl(s.Username, '[Oracle process]') User_Name,
s.Terminal Terminal, s.Program Program, St.VALUE Criteria_Value
FROM V$sesstat St, V$session s, V$process p
WHERE St.Sid = s.Sid
AND St.Statistic# = To_Number('38')
AND ('ALL' = 'ALL' OR s.Status = 'ALL')
AND p.Addr = s.Paddr
ORDER BY St.VALUE DESC, p.Spid ASC, s.Username ASC, s.Osuser ASC

8、檢視鎖（lock）情況
SELECT /* RULE */ Ls.Osuser Os_User_Name, Ls.Username User_Name,Decode(Ls.TYPE,
'RW', 'Row wait enqueue lock', 'TM', 'DML enqueue lock','TX', 'Transaction enqueue lock', 'UL', 'User supplied lock') Lock_Type,o.Object_Name OBJECT,Decode(Ls.Lmode,1, NULL, 2, 'Row Share', 3, 'Row Exclusive',
4, 'Share', 5, 'Share Row Exclusive', 6, 'Exclusive',NULL) Lock_Mode,o.Owner, Ls.Sid, Ls.Serial# Serial_Num, Ls.Id1, Ls.Id2 FROM Sys.Dba_Objects o,
(SELECT s.Osuser, s.Username, l.TYPE, l.Lmode, s.Sid, s.Serial#, l.Id1,l.Id2 FROM V$session s, V$lock l
WHERE s.Sid = l.Sid) Ls
WHERE o.Object_Id = Ls.Id1
AND o.Owner <> 'SYS'
ORDER BY o.Owner, o.Object_Name;

9、檢視等待（wait）情況
SELECT Ws.CLASS, Ws.COUNT COUNT, SUM(Ss.VALUE) Sum_Value
FROM V$waitstat Ws, V$sysstat Ss
WHERE Ss.NAME IN ('db block gets', 'consistent gets')
GROUP BY Ws.CLASS, Ws.COUNT;

10、求process/session的狀態
SELECT p.Pid, p.Spid, s.Program, s.Sid, s.Serial#
FROM V$process p, V$session s
WHERE s.Paddr = p.Addr;

11、求誰阻塞了某個session(10g)
SELECT Sid, Username, Event, Blocking_Session, Seconds_In_Wait, Wait_Time
FROM V$session
WHERE State IN ('WAITING')
AND Wait_Class != 'Idle';

12、查會話的阻塞
col user_name format a32
SELECT /* rule */ Lpad(' ', Decode(l.Xidusn, 0, 3, 0)) || l.Oracle_Username User_Name,
o.Owner, o.Object_Name, s.Sid, s.Serial#
FROM V$locked_Object l, Dba_Objects o, V$session s
WHERE l.Object_Id = o.Object_Id
AND l.Session_Id = s.Sid
ORDER BY o.Object_Id, Xidusn DESC;
col username format a15
col lock_level format a8
col owner format a18
col object_name format a32
SELECT /* rule */ s.Username,Decode(l.TYPE, 'tm', 'table lock', 'tx', 'row lock', NULL) Lock_Level,
o.Owner, o.Object_Name, s.Sid, s.Serial#
FROM V$session s, V$lock l, Dba_Objects o
WHERE l.Sid = s.Sid
AND l.Id1 = o.Object_Id( )
AND s.Username IS NOT NULL;

13、求等待的事件及會話資訊/求會話的等待及會話資訊
SELECT Se.Sid, s.Username, Se.Event, Se.Total_Waits, Se.Time_Waited,Se.Average_Wait
FROM V$session s, V$session_Event Se
WHERE s.Username IS NOT NULL
AND Se.Sid = s.Sid
AND s.Status = 'ACTIVE'
AND Se.Event NOT LIKE '%SQL*Net%'
ORDER BY s.Username;
SELECT s.Sid, s.Username, Sw.Event, Sw.Wait_Time, Sw.State,Sw.Seconds_In_Wait
FROM V$session s, V$session_Wait Sw
WHERE s.Username IS NOT NULL
AND Sw.Sid = s.Sid
AND Sw.Event NOT LIKE '%SQL*Net%'
ORDER BY s.Username;

14、求會話等待的file_id/block_id
col event format a24
col p1text format a12
col p2text format a12
col p3text format a12
SELECT Sid, Event, P1text, P1, P2text, P2, P3text, P3
FROM V$session_Wait
WHERE Event NOT LIKE '%SQL%'
AND Event NOT LIKE '%rdbms%'
AND Event NOT LIKE '%mon%'
ORDER BY Event;
SELECT NAME, Wait_Time
FROM V$latch l
WHERE EXISTS (SELECT 1
FROM (SELECT Sid, Event, P1text, P1, P2text, P2, P3text, P3
FROM V$session_Wait
WHERE Event NOT LIKE '%SQL%'
AND Event NOT LIKE '%rdbms%'
AND Event NOT LIKE '%mon%') x
WHERE x.P1 = l.Latch#);

15、求會話等待的物件
col owner format a18
col segment_name format a32
col segment_type format a32
SELECT Owner, Segment_Name, Segment_Type
FROM Dba_Extents
WHERE File_Id = &File_Id
AND &Block_Id BETWEEN Block_Id AND Block_Id Blocks - 1;

16、求出某個程式，並對它進行跟蹤
SELECT s.Sid, s.Serial#
FROM V$session s, V$process p
WHERE s.Paddr = p.Addr
AND p.Spid = &1;
Exec Dbms_System.Set_Sql_Trace_In_Session(&1, &2, TRUE);
Exec Dbms_System.Set_Sql_Trace_In_Session(&1, &2, FALSE);

17、求當前session的跟蹤檔案
SELECT P1.VALUE || '/' || P2.VALUE || '_ora_' || p.Spid || '.ora' Filename
FROM V$process p, V$session s, V$parameter P1, V$parameter P2
WHERE P1.NAME = 'user_dump_dest'
AND P2.NAME = 'instance_name'
AND p.Addr = s.Paddr
AND s.Audsid = Userenv('SESSIONID')
AND p.Background IS NULL
AND Instr(p.Program, 'CJQ') = 0;

18、求出鎖定的物件
SELECT Do.Object_Name, Session_Id, Process, Locked_Mode
FROM V$locked_Object Lo, Dba_Objects Do
WHERE Lo.Object_Id = Do.Object_Id;

19、DB_Cache建議
SELECT size_for_estimate, buffers_for_estimate, estd_physical_read_factor, estd_physical_reads
FROM V$DB_CACHE_ADVICE
WHERE name = 'DEFAULT'
AND block_size = (SELECT value FROM V$PARAMETER WHERE name = 'db_block_size')

AND advice_status = 'ON';

20、檢視各項SGA相關引數：SGA，SGASTAT
select substr(name,1,10) name,substr(value,1,10) value
from v$parameter where name = 'log_buffer';
select * from v$sgastat ;
select * from v$sga;
show parameters area_size #檢視各項區域記憶體引數，其中sort_area為排序引數用；

各項檢視建議引數值：V$DB_CACHE_ADVICE、V$SHARED_POOL_ADVICE），關於PGA
也有相關檢視V$PGA_TARGET_ADVICE 等。

21、記憶體使用鎖定在實體記憶體：
AIX 5L（AIX 4.3.3 以上）
logon aix as root
cd /usr/samples/kernel
./vmtune (資訊如下) v_pingshm已經是1
./vmtune -S 1
然後oracle使用者修改initSID.ora 中 lock_sga = true

重新啟動資料庫
HP UNIX
Root身份登陸
Create the file "/etc/privgroup": vi /etc/privgroup
Add line "dba MLOCK" to file
As root, run the command "/etc/setprivgrp -f /etc/privgroup":
$/etc/setprivgrp -f /etc/privgroup
oracle使用者修改initSID.ora中lock_sga=true
重新啟動資料庫
SOLARIS (solaris2.6以上)
8i版本以上資料庫預設使用隱藏引數 use_ism = true ，自動鎖定SGA於記憶體中,不用設定
lock_sga, 如果設定 lock_sga =true 使用非 root 使用者啟動資料庫將返回錯誤。
WINDOWS （作用不大）
不能設定lock_sga=true,可以透過設定pre_page_sga=true,使得資料庫啟動的時候就把所有內
存頁裝載，這樣可能起到一定的作用。
22、記憶體引數調整
資料緩衝區命中率
select value from v$sysstat where name ='physical reads';
select value from v$sysstat where name ='physical reads direct';
select value from v$sysstat where name ='physical reads direct (lob)';
select value from v$sysstat where name ='consistent gets';
select value from v$sysstat where name = 'db block gets';
這裡命中率的計算應該是
令 x = physical reads direct physical reads direct (lob)
命中率 =100 - ( physical reads - x) / (consistent gets db block gets - x)*100
通常如果發現命中率低於90%,則應該調整應用可可以考慮是否增大資料緩衝區；
共享池的命中率
select sum(pinhits)/sum(pins)*100 "hit radio" from v$librarycache;
假如共享池的命中率低於95%,就要考慮調整應用（通常是沒使用bind var ）或者增加記憶體；
關於排序部分
select name,value from v$sysstat where name like '%sort%';
假如我們發現sorts (disk)/ (sorts (memory) sorts (disk))的比例過高，則通常意味著
sort_area_size 部分記憶體較小，可考慮調整相應的引數。
關於log_buffer
select name,value from v$sysstat
where name in('redo entries','redo buffer allocation retries');
假如 redo buffer allocation retries/ redo entries 的比例超過1%我們就可以考慮增大log_buffer

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July 28
oracle 常用SQL查詢，望對大家有所啟示
1、檢視錶空間的名稱及大小
select t.tablespace_name, round(sum(bytes/(1024*1024)),0) ts_size
from dba_tablespaces t, dba_data_files d
where t.tablespace_name = d.tablespace_name
group by t.tablespace_name;
2、檢視錶空間物理檔案的名稱及大小
select tablespace_name, file_id, file_name,
round(bytes/(1024*1024),0) total_space
from dba_data_files
order by tablespace_name;
3、檢視回滾段名稱及大小
select segment_name, tablespace_name, r.status,
(initial_extent/1024) InitialExtent,(next_extent/1024) NextExtent,
max_extents, v.curext CurExtent
From dba_rollback_segs r, v$rollstat v
Where r.segment_id = v.usn( )
order by segment_name ;
4、檢視控制檔案
select name from v$controlfile;
5、檢視日誌檔案
select member from v$logfile;
6、檢視錶空間的使用情況
select sum(bytes)/(1024*1024) as free_space,tablespace_name
from dba_free_space
group by tablespace_name;

SELECT A.TABLESPACE_NAME,A.BYTES TOTAL,B.BYTES USED, C.BYTES FREE,
(B.BYTES*100)/A.BYTES "% USED",(C.BYTES*100)/A.BYTES "% FREE"
FROM SYS.SM$TS_AVAIL A,SYS.SM$TS_USED B,SYS.SM$TS_FREE C
WHERE A.TABLESPACE_NAME=B.TABLESPACE_NAME AND A.TABLESPACE_NAME=C.TABLESPACE_NAME;
7、檢視資料庫庫物件
select owner, object_type, status, count(*) count# from all_objects group by owner, object_type, status;
8、檢視資料庫的版本　
Select version FROM Product_component_version
Where SUBSTR(PRODUCT,1,6)='Oracle';
9、檢視資料庫的建立日期和歸檔方式
Select Created, Log_Mode, Log_Mode From V$Database;
10、捕捉執行很久的SQL
column username format a12
column opname format a16
column progress format a8

select username,sid,opname,
round(sofar*100 / totalwork,0) || '%' as progress,
time_remaining,sql_text
from v$session_longops , v$sql
where time_remaining <> 0
and sql_address = address
and sql_hash_value = hash_value
/
11。檢視資料表的引數資訊
SELECT partition_name, high_value, high_value_length, tablespace_name,
pct_free, pct_used, ini_trans, max_trans, initial_extent,
next_extent, min_extent, max_extent, pct_increase, FREELISTS,
freelist_groups, LOGGING, BUFFER_POOL, num_rows, blocks,
empty_blocks, avg_space, chain_cnt, avg_row_len, sample_size,
last_analyzed
FROM dba_tab_partitions
--WHERE table_name = :tname AND table_owner = :towner
ORDER BY partition_position

12.檢視還沒提交的事務
select * from v$locked_object;
select * from v$transaction;
13。查詢object為哪些程式所用
select
p.spid,
s.sid,
s.serial# serial_num,
s.username user_name,
a.type object_type,
s.osuser os_user_name,
a.owner,
a.object object_name,
decode(sign(48 - command),
1,
to_char(command), 'Action Code #' || to_char(command) ) action,
p.program oracle_process,
s.terminal terminal,
s.program program,
s.status session_status
from v$session s, v$access a, v$process p
where s.paddr = p.addr and
s.type = 'USER' and
a.sid = s.sid and
a.object='SUBSCRIBER_ATTR'
order by s.username, s.osuser

14。回滾段檢視
select rownum, sys.dba_rollback_segs.segment_name Name, v$rollstat.extents
Extents, v$rollstat.rssize Size_in_Bytes, v$rollstat.xacts XActs,
v$rollstat.gets Gets, v$rollstat.waits Waits, v$rollstat.writes Writes,
sys.dba_rollback_segs.status status from v$rollstat, sys.dba_rollback_segs,
v$rollname where v$rollname.name( ) = sys.dba_rollback_segs.segment_name and
v$rollstat.usn ( ) = v$rollname.usn order by rownum

15。耗資源的程式（top session）
select s.schemaname schema_name, decode(sign(48 - command), 1,
to_char(command), 'Action Code #' || to_char(command) ) action, status
session_status, s.osuser os_user_name, s.sid, p.spid , s.serial# serial_num,
nvl(s.username, '[Oracle process]') user_name, s.terminal terminal,
s.program program, st.value criteria_value from v$sesstat st, v$session s , v$process p
where st.sid = s.sid and st.statistic# = to_number('38') and ('ALL' = 'ALL'
or s.status = 'ALL') and p.addr = s.paddr order by st.value desc, p.spid asc, s.username asc, s.osuser asc

16。檢視鎖（lock）情況
select /* RULE */ ls.osuser os_user_name, ls.username user_name,
decode(ls.type, 'RW', 'Row wait enqueue lock', 'TM', 'DML enqueue lock', 'TX',
'Transaction enqueue lock', 'UL', 'User supplied lock') lock_type,
o.object_name object, decode(ls.lmode, 1, null, 2, 'Row Share', 3,
'Row Exclusive', 4, 'Share', 5, 'Share Row Exclusive', 6, 'Exclusive', null)
lock_mode, o.owner, ls.sid, ls.serial# serial_num, ls.id1, ls.id2
from sys.dba_objects o, ( select s.osuser, s.username, l.type,
l.lmode, s.sid, s.serial#, l.id1, l.id2 from v$session s,
v$lock l where s.sid = l.sid ) ls where o.object_id = ls.id1 and o.owner
<> 'SYS' order by o.owner, o.object_name

17。檢視等待（wait）情況
SELECT v$waitstat.class, v$waitstat.count count, SUM(v$sysstat.value) sum_value
FROM v$waitstat, v$sysstat WHERE v$sysstat.name IN ('db block gets',
'consistent gets') group by v$waitstat.class, v$waitstat.count

18。檢視sga情況
SELECT NAME, BYTES FROM SYS.V_$SGASTAT ORDER BY NAME ASC

19。檢視catched object
SELECT owner, name, db_link, namespace,
type, sharable_mem, loads, executions,
locks, pins, kept FROM v$db_object_cache

20。檢視V$SQLAREA
SELECT SQL_TEXT, SHARABLE_MEM, PERSISTENT_MEM, RUNTIME_MEM, SORTS,
VERSION_COUNT, LOADED_VERSIONS, OPEN_VERSIONS, USERS_OPENING, EXECUTIONS,
USERS_EXECUTING, LOADS, FIRST_LOAD_TIME, INVALIDATIONS, PARSE_CALLS, DISK_READS,
BUFFER_GETS, ROWS_PROCESSED FROM V$SQLAREA

21。檢視object分類數量
select decode (o.type#,1,'INDEX' , 2,'TABLE' , 3 , 'CLUSTER' , 4, 'VIEW' , 5 ,
'SYNONYM' , 6 , 'SEQUENCE' , 'OTHER' ) object_type , count(*) quantity from
sys.obj$ o where o.type# > 1 group by decode (o.type#,1,'INDEX' , 2,'TABLE' , 3
, 'CLUSTER' , 4, 'VIEW' , 5 , 'SYNONYM' , 6 , 'SEQUENCE' , 'OTHER' ) union select
'COLUMN' , count(*) from sys.col$ union select 'DB LINK' , count(*) from

22。按使用者檢視object種類
select u.name schema, sum(decode(o.type#, 1, 1, NULL)) indexes,
sum(decode(o.type#, 2, 1, NULL)) tables, sum(decode(o.type#, 3, 1, NULL))
clusters, sum(decode(o.type#, 4, 1, NULL)) views, sum(decode(o.type#, 5, 1,
NULL)) synonyms, sum(decode(o.type#, 6, 1, NULL)) sequences,
sum(decode(o.type#, 1, NULL, 2, NULL, 3, NULL, 4, NULL, 5, NULL, 6, NULL, 1))
others from sys.obj$ o, sys.user$ u where o.type# >= 1 and u.user# =
o.owner# and u.name <> 'PUBLIC' group by u.name order by
sys.link$ union select 'CONSTRAINT' , count(*) from sys.con$

23。有關connection的相關資訊
1）檢視有哪些使用者連線
select s.osuser os_user_name, decode(sign(48 - command), 1, to_char(command),
'Action Code #' || to_char(command) ) action, p.program oracle_process,
status session_status, s.terminal terminal, s.program program,
s.username user_name, s.fixed_table_sequence activity_meter, '' query,
0 memory, 0 max_memory, 0 cpu_usage, s.sid, s.serial# serial_num
from v$session s, v$process p where s.paddr=p.addr and s.type = 'USER'
order by s.username, s.osuser
2）根據v.sid檢視對應連線的資源佔用等情況
select n.name,
v.value,
n.class,
n.statistic#
from v$statname n,
v$sesstat v
where v.sid = 71 and
v.statistic# = n.statistic#
order by n.class, n.statistic#
3）根據sid檢視對應連線正在執行的sql
select /* PUSH_SUBQ */
command_type,
sql_text,
sharable_mem,
persistent_mem,
runtime_mem,
sorts,
version_count,
loaded_versions,
open_versions,
users_opening,
executions,
users_executing,
loads,
first_load_time,
invalidations,
parse_calls,
disk_reads,
buffer_gets,
rows_processed,
sysdate start_time,
sysdate finish_time,
'>' || address sql_address,
'N' status
from v$sqlarea
where address = (select sql_address from v$session where sid = 71)

24．查詢表空間使用情況select a.tablespace_name "表空間名稱",
100-round((nvl(b.bytes_free,0)/a.bytes_alloc)*100,2) "佔用率(%)",
round(a.bytes_alloc/1024/1024,2) "容量(M)",
round(nvl(b.bytes_free,0)/1024/1024,2) "空閒(M)",
round((a.bytes_alloc-nvl(b.bytes_free,0))/1024/1024,2) "使用(M)",
Largest "最大擴充套件段(M)",
to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') "取樣時間"
from (select f.tablespace_name,
sum(f.bytes) bytes_alloc,
sum(decode(f.autoextensible,'YES',f.maxbytes,'NO',f.bytes)) maxbytes
from dba_data_files f
group by tablespace_name) a,
(select f.tablespace_name,
sum(f.bytes) bytes_free
from dba_free_space f
group by tablespace_name) b,
(select round(max(ff.length)*16/1024,2) Largest,
ts.name tablespace_name
from sys.fet$ ff, sys.file$ tf,sys.ts$ ts
where ts.ts#=ff.ts# and ff.file#=tf.relfile# and ts.ts#=tf.ts#
group by ts.name, tf.blocks) c
where a.tablespace_name = b.tablespace_name and a.tablespace_name = c.tablespace_name

25. 查詢表空間的碎片程度

select tablespace_name,count(tablespace_name) from dba_free_space group by tablespace_name
having count(tablespace_name)>10;

alter tablespace name coalesce;
alter table name deallocate unused;

create or replace view ts_blocks_v as
select tablespace_name,block_id,bytes,blocks,'free space' segment_name from dba_free_space
union all
select tablespace_name,block_id,bytes,blocks,segment_name from dba_extents;

select * from ts_blocks_v;

select tablespace_name,sum(bytes),max(bytes),count(block_id) from dba_free_space
group by tablespace_name;

26.檢視有哪些例項在執行：

select * from v$active_instances;
12:15 PM | Add a comment | Permalink | Blog it | Oracle
ORACLE效能調優原則
資料庫的硬體配置：CPU、記憶體、網路條件
1. CPU：在任何機器中CPU的資料處理能力往往是衡量計算機效能的一個標誌，並且ORACLE是一個提供並行能力的資料庫系統，在CPU方面的要求就更高了，如果執行佇列數目超過了CPU處理的數目，效能就會下降，我們要解決的問題就是要適當增加CPU的數量了，當然我們還可以將需要許多資源的程式KILL掉；

2. 記憶體：衡量機器效能的另外一個指標就是記憶體的多少了，在ORACLE中記憶體和我們在建資料庫中的交換區進行資料的交換，讀資料時，磁碟I/O必須等待物

Oracle日常效能檢視常用語句

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