本文已参与「新人创作礼」活动，一起开启掘金创作之路
文中使用的Oracle版本为10g。
1. 查找当前表级锁
select sess.sid,
sess.serial#,
lo.oracle_username,
lo.os_user_name,
ao.object_name,
lo.locked_mode
from v$locked_object lo,
dba_objects ao,
v$session sess
where ao.object_id = lo.object_id
and lo.session_id = sess.sid;
2. 杀掉锁表进程
alter system kill session '436,35123';
3. RAC环境中锁查找
SELECT inst_id,
DECODE(request,0,'Holder: ','Waiter: ')||sid sess,
id1, id2, lmode, request, type,block,ctime
FROM GV$LOCK
WHERE (id1, id2, type) IN
(SELECT id1, id2, type FROM GV$LOCK WHERE request>0)
ORDER BY id1, request;
4. 监控当前数据库谁在运行什么
select osuser, username, sql_text
from v$session a, v$sqltext b
where a.sql_address =b.address
order by address, piece;
5. 使用CPU多的用户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$sesstat c
where c.statistic#=12 and
c.sid=a.sid and
a.paddr=b.addr
order by value desc;
6. 查看死锁信息
SELECT (SELECT username
FROM v$session
WHERE SID = a.SID) blocker, a.SID, 'is blocking',
(SELECT username
FROM v$session
WHERE SID = b.SID) blockee, b.SID
FROM v$lock a, v$lock b
WHERE a.BLOCK = 1
AND b.request > 0
AND a.id1 = b.id1
AND a.id2 = b.id2;
7. 查询具有最高等待的对象
SELECT o.OWNER,o.object_name, o.object_type, a.event,
SUM (a.wait_time + a.time_waited) total_wait_time
FROM v$active_session_history a, dba_objects o
WHERE a.sample_time BETWEEN SYSDATE - 30 / 2880 AND SYSDATE
AND a.current_obj# = o.object_id
GROUP BY o.OWNER,o.object_name, o.object_type, a.event
ORDER BY total_wait_time DESC;
SELECT a.session_id, s.osuser, s.machine, s.program, o.owner,
o.object_name,o.object_type, a.event,
SUM (a.wait_time + a.time_waited) total_wait_time
FROM v$active_session_history a, dba_objects o, v$session s
WHERE a.sample_time BETWEEN SYSDATE - 30 / 2880 AND SYSDATE
AND a.current_obj# = o.object_id
AND a.session_id = s.SID
GROUP BY o.owner,
o.object_name,o.object_type,
a.event,a.session_id,
s.program, s.machine,s.osuser
ORDER BY total_wait_time DESC;
8. 查询当前连接会话数
select s.value,s.sid,a.username
from v$sesstat S,v$statname N,v$session A
where n.statistic#=s.statistic#
and name='session pga memory'
and s.sid=a.sid
order by s.value;
9. 等待最多的用户
SELECT s.SID, s.username,
SUM (a.wait_time + a.time_waited) total_wait_time
FROM v$active_session_history a, v$session s
WHERE a.sample_time BETWEEN SYSDATE - 30 / 2880 AND SYSDATE
GROUP BY s.SID, s.username
ORDER BY total_wait_time DESC;
10. 等待最多的会话
SELECT a.program, a.session_id, a.user_id,
d.username, s.sql_text,
SUM (a.wait_time + a.time_waited) total_wait_time
FROM v$active_session_history a, v$sqlarea s, dba_users d
WHERE a.sample_time BETWEEN SYSDATE - 30 / 2880 AND SYSDATE
AND a.sql_id = s.sql_id
AND a.user_id = d.user_id
GROUP BY a.program, a.session_id, a.user_id, s.sql_text, d.username;
11. 查看消耗资源最多的SQL
SELECT hash_value, executions,
buffer_gets, disk_reads,parse_calls
FROM V$SQLAREA
WHERE buffer_gets > 10000000 OR disk_reads > 1000000
ORDER BY buffer_gets + 100 * disk_reads DESC;
12. 查看某条SQL语句的资源消耗
SELECT hash_value,buffer_gets,disk_reads,
executions,parse_calls
FROM V$SQLAREA
WHERE hash_Value = 228801498
AND address = hextoraw('CBD8E4B0');
13. 查询会话执行的实际SQL
SELECT a.SID,a.username,s.sql_text
FROM v$session a, v$sqltext s
WHERE a.sql_address = s.address
AND a.sql_hash_value = s.hash_value
AND a.status = 'ACTIVE'
ORDER BY a.username, a.SID, s.piece;
14. 显示正在等待锁的所有会话
SELECT * FROM DBA_WAITERS;
15. 查询表空间使用情况
SELECT UPPER(F.TABLESPACE_NAME) "表空间名",
D.TOT_GROOTTE_MB "表空间大小(M)",
D.TOT_GROOTTE_MB - F.TOTAL_BYTES "已使用空间(M)",
TO_CHAR(ROUND((D.TOT_GROOTTE_MB - F.TOTAL_BYTES) / D.TOT_GROOTTE_MB * 100,2),'990.99') || '%' "使用比",
F.TOTAL_BYTES "空闲空间(M)",
F.MAX_BYTES "最大块(M)"
FROM (SELECT TABLESPACE_NAME,
ROUND(SUM(BYTES) / (1024 * 1024), 2) TOTAL_BYTES,
ROUND(MAX(BYTES) / (1024 * 1024), 2) MAX_BYTES
FROM SYS.DBA_FREE_SPACE
GROUP BY TABLESPACE_NAME) F,
(SELECT DD.TABLESPACE_NAME,
ROUND(SUM(DD.BYTES) / (1024 * 1024), 2) TOT_GROOTTE_MB
FROM SYS.DBA_DATA_FILES DD
GROUP BY DD.TABLESPACE_NAME) D
WHERE D.TABLESPACE_NAME = F.TABLESPACE_NAME
ORDER BY 1;
16. 查询表空间的free space
select tablespace_name,
count(*) as extends,
round(sum(bytes) / 1024 / 1024, 2) as MB,
sum(blocks) as blocks
from dba_free_space
group by tablespace_name;
17. 查询表空间的总容量
select tablespace_name, sum(bytes) / 1024 / 1024 as MB
from dba_data_files
group by tablespace_name;
18. 查询表空间使用率
select total.tablespace_name,
round(total.MB, 2) as Total_MB,
round(total.MB - free.MB, 2) as Used_MB,
round((1 - free.MB / total.MB) * 100, 2) || '%' as Used_Pct
from (select tablespace_name, sum(bytes) / 1024 / 1024 as MB
from dba_free_space
group by tablespace_name) free,
(select tablespace_name, sum(bytes) / 1024 / 1024 as MB
from dba_data_files
group by tablespace_name) total
where free.tablespace_name = total.tablespace_name;
19. 查询数据库最大连接数
select value
from v$parameter
where name = 'processes';
20. 对象不再存在(ORA-08103)解决方法
先查询出“xxx”对象信息
SQL> select obj#,dataobj#,name,type#,owner# from obj$ where name='xxx';
OBJ# DATAOBJ# NAME TYPE# OWNER#
----- ---------- ---------------- ---------- ----------
5368 xxx 5 1
5993 xxx 42 66
根据obj#对应的id值精确定位到对象（根据OWNER字段判断对象归属，这个不再详述）
SQL> select obj#,dataobj#,name,type#,owner# from obj$ where obj#=5993;
OBJ# DATAOBJ# NAME TYPE# OWNER#
----- ---------- ---------------- ---------- ----------
5993 xxx 42 66
确认obj#对象后使用delete from命令进行删除
SQL> delete from obj$ where obj#=5993;
已删除 1 行。
SQL> commit;
提交完成。
提交之后再重新查询对象
SQL> select obj#,dataobj#,name,type#,owner# from obj$ where name='xxx';
OBJ# DATAOBJ# NAME TYPE# OWNER#
----- ---------- ---------------- ---------- ----------
5368 xxx 5 1
