分析数据库性能的SQL

--用于查看哪些实例的哪些操作使用了大量的临时段

SELECT to_number(decode(SID, 65535, NULL, SID)) sid,
operation_type OPERATION,trunc(EXPECTED_SIZE/1024) ESIZE,
trunc(ACTUAL_MEM_USED/1024) MEM, trunc(MAX_MEM_USED/1024) "MAX MEM",
NUMBER_PASSES PASS, trunc(TEMPSEG_SIZE/1024) TSIZE
FROM V$SQL_WORKAREA_ACTIVE
ORDER BY 1,2;

---查询有热块查询的SQL语句

select hash_value
from v$sqltext a,
(select distinct a.owner,a.segment_name,a.segment_type from
dba_extents a,
(select dbarfil,dbablk
from (select dbarfil,dbablk
from x$bh order by tch desc) where rownum < 11) b
where a.RELATIVE_FNO = b.dbarfil
and a.BLOCK_ID <= b.dbablk and a.block_id + a.blocks > b.dbablk) b
where a.sql_text like '%'b.segment_name'%' and b.segment_type = 'TABLE'
order bya.hash_value,a.address,a.piece;

--全表扫描

select opname,target,b.num_rows,b.tablespace_name,count(target) from v$session_longops a,all_all_tables b
where a.TARGET=b.owner'.'b.table_name
having count(target)>10 group by opname,target,b.num_rows,b.tablespace_name

--查看磁盘排序和缓存排序次数

selectto_char(sn.snap_time,'yyyy-mm-dd hh24') time_,
avg(newmen.value - oldmen.value) sorts_memeory,
avg(newdsk.value - olddsk.value) disk_sort
fromstats$sysstat oldmen,
stats$sysstat newmen,
stats$sysstat newdsk,
stats$sysstat olddsk,
stats$snapshot sn
where newdsk.snap_id=sn.snap_id
and olddsk.snap_id=sn.snap_id-1
and newmen.snap_id=sn.snap_id
and newdsk.snap_id=sn.snap_id -1
and oldmen.name='sorts (memory)'
and newmen.name='sorts (memory)'
and olddsk.name='sorts (disk)'
and newdsk.name='sorts (disk)'
group byto_char(sn.snap_time,'yyyy-mm-dd hh24')

--执行最慢的前10个SQL？？？

select * from (
select
to_char(snap_time,'dd Mon HH24:mi:ss') mydate,
executions exec,
loadsloads,
parse_callsparse,
disk_reads reads,
buffer_getsgets,
rows_processed rows_proc,
sortssorts,
sql_text,
hash_value
from
perfstat.stats$sql_summary sql,
perfstat.stats$snapshot sn
where
sql.snap_id >
(select min(snap_id) min_snap
from stats$snapshot where snap_time > sysdate-$days_back)
and
sql.snap_id = sn.snap_id
order by $sortskey desc)tt where rownum<11;

--SQL缓存池的命中率查询（pinhitratio，gethitratio应该大于90%以上）

select namespace,gethitratio,pinhitratio,reloads,invalidations
from v$librarycache
where namespace in ('SQL AREA','TABLE/PROCEDURE','BODY','TRIGGER')

--数据库的常规参数我就不说了，除了V$parameter中的常规参数外，Oracle还有大量的隐含参数，下面的语句就可以查询到数据库的所有隐含参数以及其值与参数的描述。


SELECT NAME
,VALUE
,decode(isdefault, 'TRUE','Y','N') as "Default"
,decode(ISEM,'TRUE','Y','N') as SesMod
,decode(ISYM,'IMMEDIATE', 'I',
'DEFERRED', 'D',
'FALSE', 'N') as SysMod
,decode(IMOD,'MODIFIED','U',
'SYS_MODIFIED','S','N') as Modified
,decode(IADJ,'TRUE','Y','N') as Adjusted
,description
FROM ( --GV$SYSTEM_PARAMETER
SELECT x.inst_id as instance
,x.indx+1
,ksppinm as NAME
,ksppity
,ksppstvl as VALUE
,ksppstdf as isdefault
,decode(bitand(ksppiflg/256,1),1,'TRUE','FALSE') as ISEM
,decode(bitand(ksppiflg/65536,3),
1,'IMMEDIATE',2,'DEFERRED','FALSE') as ISYM
,decode(bitand(ksppstvf,7),1,'MODIFIED','FALSE') as IMOD
,decode(bitand(ksppstvf,2),2,'TRUE','FALSE') as IADJ
,ksppdesc as DESCRIPTION
FROM x$ksppi x
,x$ksppsv y
WHERE x.indx = y.indx
AND substr(ksppinm,1,1) = '_'
AND x.inst_id = USERENV('Instance')
)
ORDER BY NAME

--想知道现在哪个用户正在利用临时段吗？这个语句将告诉你哪个用户正在利用临时段。

SELECT b.tablespace, b.segfile#, b.segblk#, b.blocks, a.sid, a.serial#,
a.username, a.osuser, a.status,c.sql_text
FROM v$session a,v$sort_usage b, v$sql c
WHERE a.saddr = b.session_addr
AND a.sql_address = c.address(+)
ORDER BY b.tablespace, b.segfile#, b.segblk#, b.blocks;

--查看磁盘碎片

select tablespace_name,sqrt(max(blocks)/sum(blocks))*
(100/sqrt(sqrt(count(blocks)))) FSFI
from dba_free_space
group by tablespace_name order by 1

1.查看表空间的名称及大小

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.查看表空间物理文件的名称及大小

select tablespace_name, file_id, file_name,
round(bytes/(1024*1024),0) total_space
from dba_data_files
order by tablespace_name;

3.查看回滚段名称及大小

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

15。耗资源的进程（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_valuefrom 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。

查看锁（lock）情况

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 ) lswhere o.object_id = ls.id1 ando.owner
<> 'SYS' order by o.owner, o.object_name

--查看低效率的SQL语句

SELECT EXECUTIONS , DISK_READS, BUFFER_GETS,
ROUND((BUFFER_GETS-DISK_READS)/BUFFER_GETS,2) Hit_radio,
ROUND(DISK_READS/EXECUTIONS,2) Reads_per_run,
SQL_TEXT
FROM V$SQLAREA
WHEREEXECUTIONS>0
AND BUFFER_GETS > 0
AND (BUFFER_GETS-DISK_READS)/BUFFER_GETS < 0.8
ORDER BY 4 DESC