死锁后的解决办法
如果死锁不能自动释放，就需要我们手工的 kill session
生成Kill Session语句
- 查看有无死锁对象，如有 kill session
SELECT 'alter system kill session ''' || sid || ',' || serial# || ''';' "Deadlock" FROM v$session WHERE sid IN (SELECT sid FROM v$lock WHERE block = 1);
如果有，会返回类似与如下的信息：
alter system kill session '761,876'; .....
kill session：
执行 alter system kill session ‘761,876’(sid 为 761);
注意： 应当注意对于 sid 在 100 以下的应当谨慎，可能该进程对应某个application，如对应某个事务,可以 kill
查看导致死锁的 SQL
SELECT s.sid, q.sql_text FROM v$sqltext q, v$session s WHERE q.address = s.sql_address AND s.sid = &sid -- 这个&sid 是第一步查询出来的 ORDER BY piece;
执行后，输入对应的sid即可查看对应的sql.
查看谁锁了谁
SELECT s1.username || '@' || s1.machine || ' ( SID=' || s1.sid || ' ) is blocking ' || s2.username || '@' || s2.machine || ' ( SID=' || s2.sid || ' ) ' AS blocking_status FROM v$lock l1, v$session s1, v$lock l2, v$session s2 WHERE s1.sid = l1.sid AND s2.sid = l2.sid AND l1.BLOCK = 1 AND l2.request > 0 AND l1.id1 = l2.id1 AND l2.id2 = l2.id2;
或者
推荐这个，因为使用的是 v$locked_object
SELECT LPAD(' ', DECODE(l.xidusn, 0, 3, 0)) || l.oracle_username User_name, o.owner, o.object_name, o.object_type, s.sid, s.serial# FROM v$locked_object l, dba_objects o, v$session s WHERE l.object_id = o.object_id AND l.session_id = s.sid ORDER BY o.object_id, xidusn DESC;
V$LOCKED_OBJECT只能报发生等待的表级锁,不能报发生等待的行级锁。
ORA-00054 资源正忙，要求指定 NOWAIT
演示：
select * from emp for update ;--通过for update 获取一个排它锁
SQL>select object_name as 对象名称,s.sid,s.serial#,p.spid as 系统进程号 from v$locked_object l , dba_objects o , v$session s , v$process p where l.object_id=o.object_id and l.session_id=s.sid and s.paddr=p.addr; 对象名称 SID SERIAL# 系统进程号 -------------------------------------------------------------------------------- ---------- ---------- ------------------------ EMP 1411 8865 32720
在另外一个会话中执行
ALTER SYSTEM KILL SESSION '1411,8865';
查询绑定变量使用的实际值
1, SQL还在shared pool中，没有被aged out 替换SQL ID 值即可
select sql_id, name, datatype_string, last_captured, value_string from v$sql_bind_capture where sql_id = '7nqt558g5gmyr' order by LAST_CAPTURED, POSITION;
2.请自行替换sql_id，此时是从awr中查询(sql 被 aged out 出 shared pool)
select instance_number, sql_id, name, datatype_string, last_captured, value_string from dba_hist_sqlbind where sql_id = 'fahv8x6ngrb50' order by LAST_CAPTURED, POSITION;
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$session_Wait group by event order by 4 ;
回滚段的争用情况
select name, waits, gets, waits / gets "Ratio" from v$rollstat a, v$rollname b where a.usn = b.usn;
查看回滚段名称及大小
SELECT segment_name, tablespace_name, r.status, (initial_extent / 1024) initialextent, (next_extent / 1024) nextextent, max_extents, v.curext curextent FROM dba_rollback_segs r, v$rollstat v WHERE r.segment_id = v.usn(+) ORDER BY segment_name;
查看控制文件
SELECT NAME FROM v$controlfile;
查看日志文件
SELECT MEMBER FROM v$logfile;
查看前台正在发出的SQL语句
select user_name,sql_text from v$open_cursor where sid in (select sid from (select sid,serial#,username,program from v$session where status='ACTIVE'));
数据表占用空间大小情况
select segment_name, tablespace_name, bytes, blocks from user_segments where segment_type = 'TABLE' ORDER BY bytes DESC, blocks DESC;
查看表空间碎片大小
select tablespace_name,round(sqrt(max(blocks)/sum(blocks))* (100/sqrt(sqrt(count(blocks)))),2) FSFI from dba_free_space group by tablespace_name order by 1;
查看表空间占用磁盘情况
select b.file_id 文件ID号, b.tablespace_name 表空间名, b.bytes 字节数, (b.bytes-sum(nvl(a.bytes,0))) 已使用, sum(nvl(a.bytes,0)) 剩余空间, sum(nvl(a.bytes,0))/(b.bytes)*100 剩余百分比 from dba_free_space a,dba_data_files b where a.file_id=b.file_id group by b.tablespace_name,b.file_id,b.bytes order by b.file_id;
查看表的大小，倒序排列
每张表都是作为“段”来存储的，可以通过user_segments视图查看其相应信息。
段（segments）的定义：如果创建一个堆组织表，则该表就是一个段
SELECT SEGMENT_NAME, SUM(BYTES) / 1024 / 1024 MBYTESE FROM USER_SEGMENTS WHERE SEGMENT_TYPE = 'TABLE' GROUP BY SEGMENT_NAME order by MBYTESE desc;
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;
查看Oracle 表空间使用率
SELECT D.TABLESPACE_NAME, SPACE || 'M' "SUM_SPACE(M)", SPACE - NVL (FREE_SPACE, 0) || 'M' "USED_SPACE(M)", ROUND ( (1 - NVL (FREE_SPACE, 0) / SPACE) * 100, 2) || '%' "USED_RATE(%)", FREE_SPACE || 'M' "FREE_SPACE(M)" FROM ( SELECT TABLESPACE_NAME, ROUND (SUM (BYTES) / (1024 * 1024), 2) SPACE, SUM (BLOCKS) BLOCKS FROM DBA_DATA_FILES GROUP BY TABLESPACE_NAME) D, ( SELECT TABLESPACE_NAME, ROUND (SUM (BYTES) / (1024 * 1024), 2) FREE_SPACE FROM DBA_FREE_SPACE GROUP BY TABLESPACE_NAME) F WHERE D.TABLESPACE_NAME = F.TABLESPACE_NAME(+) UNION ALL --如果有临时表空间 SELECT D.TABLESPACE_NAME, SPACE || 'M' "SUM_SPACE(M)", USED_SPACE || 'M' "USED_SPACE(M)", ROUND (NVL (USED_SPACE, 0) / SPACE * 100, 2) || '%' "USED_RATE(%)", NVL (FREE_SPACE, 0) || 'M' "FREE_SPACE(M)" FROM ( SELECT TABLESPACE_NAME, ROUND (SUM (BYTES) / (1024 * 1024), 2) SPACE, SUM (BLOCKS) BLOCKS FROM DBA_TEMP_FILES GROUP BY TABLESPACE_NAME) D, ( SELECT TABLESPACE_NAME, ROUND (SUM (BYTES_USED) / (1024 * 1024), 2) USED_SPACE, ROUND (SUM (BYTES_FREE) / (1024 * 1024), 2) FREE_SPACE FROM V$TEMP_SPACE_HEADER GROUP BY TABLESPACE_NAME) F WHERE D.TABLESPACE_NAME = F.TABLESPACE_NAME(+) ORDER BY 1;
SELECT a.tablespace_name "表空间名", total "表空间大小", free "表空间剩余大小", (total - free) "表空间使用大小", total / (1024 * 1024 * 1024) "表空间大小(G)", free / (1024 * 1024 * 1024) "表空间剩余大小(G)", (total - free) / (1024 * 1024 * 1024) "表空间使用大小(G)", round((total - free) / total, 4) * 100 "使用率 %" FROM (SELECT tablespace_name, SUM(bytes) free FROM dba_free_space GROUP BY tablespace_name) a, (SELECT tablespace_name, SUM(bytes) total FROM dba_data_files GROUP BY tablespace_name) b WHERE a.tablespace_name = b.tablespace_name
查看Temp 表空间实际使用磁盘大小
Select f.tablespace_name, d.file_name "Tempfile name", round((f.bytes_free + f.bytes_used) / 1024 / 1024, 2) "total MB", round(((f.bytes_free + f.bytes_used) - nvl(p.bytes_used, 0)) / 1024 / 1024, 2) "Free MB", round(nvl(p.bytes_used, 0) / 1024 / 1024, 2) "Used MB", round((round(nvl(p.bytes_used, 0) / 1024 / 1024, 2) / round((f.bytes_free + f.bytes_used) / 1024 / 1024, 2)) * 100, 2) as "Used_Rate(%)" from SYS.V_$TEMP_SPACE_HEADER f, DBA_TEMP_FILES d, SYS.V_$TEMP_EXTENT_POOL p where f.tablespace_name(+) = d.tablespace_name and f.file_id(+) = d.file_id and p.file_id(+) = d.file_id;
查看session使用回滚段
SELECT r.name 回滚段名, s.sid, s.serial#, s.username 用户名, t.status, t.cr_get, t.phy_io, t.used_ublk, t.noundo, substr(s.program, 1, 78) 操作程序 FROM sys.v_$session s,sys.v_$transaction t,sys.v_$rollname r WHERE t.addr = s.taddr and t.xidusn = r.usn ORDER BY t.cr_get,t.phy_io;
查看当前临时表空间使用大小与正在占用临时表空间的sql语句
select sess.SID, segtype, blocks * 8 / 1000 "MB", sql_text from v$sort_usage sort, v$session sess, v$sql sql where sort.SESSION_ADDR = sess.SADDR and sql.ADDRESS = sess.SQL_ADDRESS order by blocks desc;
Temp表空间上进程的查询
select a.tablespace, b.sid, b.serial#, a.blocks,c.sql_text from v$sort_usage a,v$session b,v$sqltext c where a.session_addr = b.saddr and b.sql_address = c.address order by a.tablespace,b.sid,b.serial#,c.address, c.piece;
Temp表空间上进程的查询
select a.tablespace, b.sid, b.serial#, a.blocks,c.sql_text from v$sort_usage a,v$session b,v$sqltext c where a.session_addr = b.saddr and b.sql_address = c.address order by a.tablespace,b.sid,b.serial#,c.address, c.piece;
查看SGA区剩余可用内存
select name, sgasize/1024/1024 "Allocated(M)", bytes/1024 "**空间(K)", round(bytes/sgasize*100, 2) "**空间百分比(%)" from (select sum(bytes) sgasize from sys.v_$sgastat) s, sys.v_$sgastat f where f.name = 'free memory';
监控表空间I/O比例
select df.tablespace_name name,df.file_name "file",f.phyrds pyr, f.phyblkrd pbr,f.phywrts pyw, f.phyblkwrt pbw from v$filestat f, dba_data_files df where f.file# = df.file_id order by df.tablespace_name;
监控SGA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 ;
