分析表
analyze table tablename compute statistics for all
indexes;
analyze table tablename compute statistics for all indexed
columns;
analyze table tablename compute statistics for
table;
监控事例的等待
select
event,sum(decode(wait_Time,0,0,1)) "Prev",
sum(decode(wait_Time,0,1,0))
"Curr",count(*) "Tot"
from v$session_Wait
group by event order
by 4;
查看碎片程度高的表
SELECT segment_name table_name ,
COUNT(*) extents
FROM dba_segments WHERE owner NOT IN (SYS, SYSTEM)
GROUP BY segment_name
HAVING COUNT(*) = (SELECT MAX( COUNT(*) FROM
dba_segments GROUP BY
segment_name);
表、索引的存储情况检查
select
segment_name,sum(bytes),count(*) ext_quan from dba_extents
where
tablespace_name=&tablespace_name and segment_type=TABLE group
by tablespace_name,segment_name;
select segment_name,count(*) from
dba_extents where segment_type=INDEX and owner=&owner
group by
segment_name;
找使用CPU多的用户session
12是cpu used by this
session
select a.sid,spid,status,substr(a.program,1,40)
prog,a.terminal,osuser,value/60/100 value
from v$session a,v$process
b,v$sesstat c
where c.statistic#=12 and c.sid=a.sid and a.paddr=b.addr
order by value desc;
监控表空间的 I/O 比例
select
df.tablespace_name name,df.file_name "file",f.phyrds pyr,
f.phyblkrd
pbr,f.phywrts pyw, f.phyblkwrt pbw
from v$filestat f, dba_data_files
df
where f.file# = df.file_id
order by
df.tablespace_name;
回滚段的争用情况
select name, waits,
gets, waits/gets "Ratio"
from v$rollstat a, v$rollname b
where
a.usn = b.usn;
在某个用户下找所有的索引
select
user_indexes.table_name, user_indexes.index_name,uniqueness,
column_name
from user_ind_columns, user_indexes
where
user_ind_columns.index_name = user_indexes.index_name
and
user_ind_columns.table_name = user_indexes.table_name
order by
user_indexes.table_type,
user_indexes.table_name,
user_indexes.index_name,
column_position;
监控文件系统的 I/O 比例
select
substr(a.file#,1,2) "#", substr(a.name,1,30) "Name",
a.status, a.bytes,
b.phyrds, b.phywrts
from v$datafile a, v$filestat b
where
a.file# = b.file#;
监控 SGA 中字典缓冲区的命中率
select parameter,
gets,Getmisses , getmisses/(gets+getmisses)*100 "miss
ratio",
(1-(sum(getmisses)/ (sum(gets)+sum(getmisses))))*100 "Hit
ratio"
from v$rowcache
where gets+getmisses
<>0
group by parameter, gets, getmisses;
监控 SGA
*享缓存区的命中率，应该小于1％
select sum(pins) "Total Pins", sum(reloads)
"Total Reloads",
sum(reloads)/sum(pins) *100 libcache
from
v$librarycache;
select sum(pinhits-reloads)/sum(pins) "hit
radio",sum(reloads)/sum(pins) "reload percent"
from
v$librarycache;
监控 SGA 的命中率
select a.value + b.value
"logical_reads", c.value "phys_reads",
round(100 *
((a.value+b.value)-c.value) / (a.value+b.value)) "BUFFER HIT
RATIO"
from v$sysstat a, v$sysstat b, v$sysstat c
where
a.statistic# = 38 and b.statistic# = 39
and c.statistic# =
40;
监控 SGA 中重做日志缓存区的命中率，应该小于1％
SELECT name, gets,
misses, immediate_gets,
immediate_misses,
Decode(gets,0,0,misses/gets*100)
ratio1,
Decode(immediate_gets+immediate_misses,0,0,
immediate_misses/(immediate_gets+immediate_misses)*100)
ratio2
FROM v$latch WHERE name IN (redo allocation, redo
copy);
显示所有数据库对象的类别和大小
select count(name)
num_instances ,type ,sum(source_size) source_size ,
sum(parsed_size)
parsed_size ,sum(code_size) code_size ,sum(error_size)
error_size,
sum(source_size) +sum(parsed_size) +sum(code_size)
+sum(error_size) size_required
from dba_object_size
group by
type order by 2;
监控内存和硬盘的排序比率，最好使它小于 .10，增加
sort_area_size
SELECT name, value FROM v$sysstat WHERE name IN
(sorts (memory), sorts
(disk));
监控当前数据库谁在运行什么SQL语句
SELECT osuser,
username, sql_text from v$session a, v$sqltext b
where a.sql_address
=b.address order by address, piece;
监控字典缓冲区
SELECT
(SUM(PINS - RELOADS)) / SUM(PINS) "LIB CACHE" FROM
V$LIBRARYCACHE;
SELECT (SUM(GETS - GETMISSES - USAGE - FIXED)) /
SUM(GETS) "ROW CACHE" FROM V$ROWCACHE;
SELECT SUM(PINS) "EXECUTIONS",
SUM(RELOADS) "CACHE MISSES WHILE EXECUTING" FROM
V$LIBRARYCACHE;
后者除以前者,此比率小于1％,接近0％为好。
SELECT
SUM(GETS) "DICTIONARY GETS",SUM(GETMISSES) "DICTIONARY CACHE GET
MISSES"
FROM V$ROWCACHE
监控 MTS
select
busy/(busy+idle) "shared servers busy" from
v$dispatcher;
此值大于0.5时，参数需加大
select
sum(wait)/sum(totalq) "dispatcher waits" from v$queue where
type=dispatcher;
select count(*) from v$dispatcher;
select
servers_highwater from
v$mts;
servers_highwater接近mts_max_servers时，参数需加大
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;