监控事例的等待:
select eventsum(decode(wait_time)) prevsum(decode(wait_time)) curr
count(*)from v$session_wait group by event order by ;
回滚段的争用情况:
select namewaitsgetswaits/gets ratio fromv$rollstat av$rollname b where ausn=busn;
监控表空间的I/O比例:
selectdftablespace_namenamedffile_name filefphyrds pyrfphyblkrd pbrfphywrtspywfphyblkwrtpbw fromv$filestatfdba_data_files df
where ffile#=dffile_id
在某个用户下找所有的索引:
selectuser_indexestable_nameuser_indexesindex_nameuniqueness column_namefrom user_ind_columns user_indexes
where user_ind_columnsindex_name = user_indexesindex_name
and user_ind_columnstable_name = user_indexestable_name
order by user_indexestable_type user_indexestable_name
user_indexesindex_name column_position;
监控 SGA 的命中率
select avalue + bvalue logical_reads cvalue phys_reads
round( * ((avalue+bvalue)cvalue) / (avalue+bvalue))
BUFFER HIT RATIO
from v$sysstat a v$sysstat b v$sysstat c
where astatistic# = and bstatistic# =
and cstatistic# = ;
监控 SGA 中字典缓沖区的命中率
select parameter getsGetmisses getmisses/(gets+getmisses)* miss ratio
((sum(getmisses)/ (sum(gets)+sum(getmisses))))* Hit ratio
from v$rowcache
where gets+getmisses <>
group by parameter gets getmisses;
监控 SGA 中共享缓存区的命中率应该小于%
select sum(pins) Total Pins sum(reloads) Total Reloads
sum(reloads)/sum(pins) * libcache
from v$librarycache;
select sum(pinhitsreloads)/sum(pins) hit
radiosum(reloads)/sum(pins) reload percent
from v$librarycache;
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_sizesum(parsed_size)parsed_size
sum(code_sizecode_sizesum(er
ror_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 ;
监控 SGA 中重做日志缓存区的命中率应该小于%
SELECT name gets misses immediate_gets immediate_misses
Decode(getsmisses/gets*) ratio
Decode(immediate_gets+immediate_misses
immediate_misses/(immediate_gets+immediate_misses)*) ratio
FROM v$latch WHERE name IN (redo allocation redo copy);
监控内存和硬盘的排序比率最好使它小于增加sort_area_size
SELECT name value FROM v$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 asql_address =baddress order by address piece;
监控字典缓沖区
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$LIBRARYCACHE; 后者除以前者此比率小于%接近%为好SELECT SUM(GETS) DICTIONARY GETSSUM(GETMISSES) DICTIONARY CACHE GET MISSESFROM V$ROWCACHE
找ORACLE字符集
select * from sysprops$ where name=NLS_CHARACTERSET;
监控 MTS
select busy/(busy+idle) shared servers busy from v$dispatcher;
此值大于时参数需加大
select sum(wait)/sum(totalq) dispatcher waits from v$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_namecount(tablespace_name) from dba_free_space
group by tablespace_name
having count(tablespace_name)>;
alter tablespace name coalesce;
alter table name deallocate unused;
create or replace view ts_blocks_v as
select tablespace_nameblock_idbytesblocksfree space
segment_name from dba_free_space
union all
select tablespace_nameblock_idbytesblockssegment_name from
dba_extents;
select * from ts_blocks_v;
select tablespace_namesum(bytes)max(bytes)count(block_id) from
dba_free_space
group by tablespace_name;
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_namesum(bytes)count(*) ext_quan from dba_extents
where tablespace_name=&tablespace_name and segment_type=TABLE
group by tablespace_namesegment_name;
select segment_namecount(*) from dba_extents where
segment_type=INDEX and owner=&ownergroup by segment_name;
找使用CPU多的用户session
是cpu used by this session
select asidspidstatussubstr(aprogram)
progaterminalosuservalue// value
from v$session av$process bv$sesstat c
where cstatistic#= and csid=asid and apaddr=baddr order by
value desc;
监控log_buffer的使用情况:(值最好小于%否则增加log_buffer 的大小)
seletnamerbarvaluerenamerevalue
(rbarvalue*)/revalue||% radio
from v$sysstat rbarv$sysstat re
where rbarname=redo buffer allocation retries
and rename=redo entries;
查看运行过的SQL语句:
SELECT SQL_TEXTFROM V$SQL
