1.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(*)from v$session_wait group by event order by 4; 2.回滚段的争用情况: select name,waits,gets,waits/gets ratio fromv$rollstat a,v$rollname b where a.usn=b.usn; 3.监控表空间的I/O比例: selectdf.tablespace_namename,df.file_name "file",f.phyrds pyr,f.phyblkrd pbr,f.phywrtspyw,f.phyblkwrtpbw fromv$filestatf,dba_data_files df where f.file#=df.file_id4.在某个用户下找所有的索引: selectuser_indexes.table_name,user_indexes.index_name,uniqueness, column_namefrom 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; 5. 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$sysstat c where a.statistic# = 38 and b.statistic# = 39 and c.statistic# = 40; 6. 监控 SGA 中字典缓冲区的命中率 select parameter, gets,Getmisses , getmisses/(gets+getmisses)*100 "miss ratio", (1-(sum(getmisses)/ (sum(gets)+sum(getmisses))))*100 "Hit ratio" from v$rowcache where gets+getmisses <>0 group by parameter, gets, getmisses; 7. 监控 SGA 中共享缓存区的命中率，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;8. 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_sizecode_size,sum(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 2; 9. 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$latch WHERE name IN ('redo allocation', 'redo copy'); 10. 监控内存和硬盘的排序比率，最好使它小于10，增加sort_area_size SELECT name, value FROM v$sysstat WHERE name IN ('sorts(memory)', 'sorts (disk)'); 11. 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; 12. 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$LIBRARYCACHE; 后者除以前者,此比率小于1%,接近0%为好。SELECT SUM(GETS) "DICTIONARY GETS",SUM(GETMISSES) "DICTIONARY CACHE GET MISSES"FROM V$ROWCACHE13. 找ORACLE字符集 select * from sys.props$ where name='NLS_CHARACTERSET'; 14. 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 15. 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; 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);16. 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; 17、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$sesstat c where c.statistic#=12 and c.sid=a.sid and a.paddr=b.addr order by value desc; 18.监控log_buffer的使用情况:(值最好小于1%，否则增加log_buffer 的大小) seletname,rbar.value,re.name,re.value, (rbar.value*100)/re.value||'%' "radio" from v$sysstat rbar,v$sysstat re where rbar.name='redo buffer allocation retries' and re.name='redo entries'; 19、查看运行过的SQL语句: SELECT SQL_TEXTFROM V$SQL
select
substr(to_char(s.pct, '99.00'), 2) || '%' load,
s.executions executes,
p.sql_text
from
(
select
address,
disk_reads,
executions,
pct,
rank() over (order by disk_reads desc) ranking
from
(
select
address,
disk_reads,
executions,
100 * ratio_to_report(disk_reads) over () pct
from
sys.v_$sql
where
command_type != 47
)
where
disk_reads > 50 * executions
) s,
sys.v_$sqltext p
where
s.ranking <= 5 and
p.address = s.address
order by
1, s.address, p.piece
/
-- 逻辑读多的SQL select * from (select buffer_gets, sql_text
from v$sqlarea
where buffer_gets > 500000
order by buffer_gets desc) where rownum<=30;
-- 执行次数多的SQL select sql_text,executions from
(select sql_text,executions from v$sqlarea order by executions desc)
where rownum<81;
-- 读硬盘多的SQL select sql_text,disk_reads from
(select sql_text,disk_reads from v$sqlarea order by disk_reads desc)
where rownum<21;
-- 排序多的SQL select sql_text,sorts from
(select sql_text,sorts from v$sqlarea order by sorts desc)
where rownum<21;
--分析的次数太多，执行的次数太少，要用绑变量的方法来写sql set pagesize 600;
set linesize 120;
select substr(sql_text,1,80) "sql", count(*), sum(executions) "totexecs"
from v$sqlarea
where executions < 5
group by substr(sql_text,1,80)
having count(*) > 30
order by 2;
-- 游标的观察 set pages 300;
select sum(a.value), b.name
from v$sesstat a, v$statname b
where a.statistic# = b.statistic#
and b.name = 'opened cursors current'
group by b.name;
select count(0) from v$open_cursor;
select user_name,sql_text,count(0) from v$open_cursor
group by user_name,sql_text having count(0)>30;
--查看当前用户&username执行的SQL select sql_text from v$sqltext_with_newlines where (hash_value,address) in
(select sql_hash_value,sql_address from v$session where username='&username')
order by address,piece;