分类目录归档：Oracle

ORA-01555 caused by SQL statement below

发表于 2012 年 1 月 4 日 由 惜分飞

一.发现ORA-01555

Mon Dec 26 10:08:22 2011
ORA-01555 caused by SQL statement below (Query Duration=49146 sec, SCN: 0x0b4b.17f5ae42):
Mon Dec 26 10:08:22 2011
SELECT COMPANY_ID,
       COMPANY_MOBILE,
       TO_CHAR(NVL(REG_DATE, SYSDATE - 100), 'yyyymmddhh24miss'),
       BAK_FIELD2
  FROM TAB_XN_COMPANY
 WHERE (COMPANY_STATUS = 1 OR
       (COMPANY_STATUS = 3 AND
       NVL(UNREG_DATE, SYSDATE + 100) >=
       TO_DATE('20111226094500', 'yyyymmddhh24miss')))
   AND NVL(REG_DATE, SYSDATE - 100) <=
       TO_DATE('20111226095959', 'yyyymmddhh24miss')
   AND PAY_TYPE > 0

二.数据库状态

[oracle@ora02 ~]$ sqlplus "/ as sysdba"

SQL*Plus: Release 9.2.0.4.0 - Production on Wed Jan 4 10:48:17 2012

Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.


Connected to:
Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.4.0 - Production

SQL> show parameter undo;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
undo_management                      string      AUTO
undo_retention                       integer     10800
undo_suppress_errors                 boolean     FALSE
undo_tablespace                      string      UNDOTBS1

SQL> select sum(maxbytes)/1024/1024/1024,
   2 SUM(USER_BYTES)/1024/1024/1024 FROM dba_data_files where tablespace_NAME='UNDOTBS1';

SUM(MAXBYTES)/1024/1024/1024 SUM(USER_BYTES)/1024/1024/1024
---------------------------- ------------------------------
                  61.9999847                     32.6834106

SQL> SELECT DISTINCT STATUS "状态",
  2                  COUNT(*) "EXTENT数量",
  3                  SUM(BYTES) / 1024 / 1024 / 1024 "UNDO大小"
  4    FROM DBA_UNDO_EXTENTS
  5   GROUP BY STATUS;

状态      EXTENT数量   UNDO大小
--------- ---------- ----------
ACTIVE             1 .000976563
EXPIRED         2549 31.2333298
UNEXPIRED          3 .000175476

通过undo_retention保留时间为10800秒，而该sql执行了49146秒，在这49146秒钟，TAB_XN_COMPANY表中的数据被修改，而且被修改的undo数据在10800秒后被覆盖导致，导致原查询语句不能获取到scn小于或者等于查询时候的数据块内容(在undo中)，所以出现ORA-01555。从这里也可以看出来，在undo空间还剩余的情况下，如果超过了undo_retention限制，undo内容还是有可能被覆盖，而不是使用未使用的undo

三.出现ORA-1555原因
The ORA-1555 errors can happen when a query is unable to access enough undo to build a copy of the data at the time the query started. Committed “versions” of blocks are maintained along with newer uncommitted “versions” of those blocks so that queries can access data as it existed in the database at the time of the query. These are referred to as “consistent read” blocks and are maintained using Oracle undo management.
就是一个查询要访问某个数据块，而这个数据块在这个查询执行过程中修改过，那么该查询需要查询undo中数据块，而undo中该数据块已经不存在，从而出现ORA-1555

四.ORA-1555解决方法
Case 1 – Rollback Overwritten
1.缩短sql运行时间
2.增加undo_retention，这个同时需要考虑undo空间大小
3.减少commit(rollback)次数
4.在一条sql中尽量使数据块访问一次
4.1)Using a full table scan rather than an index lookup
4.2)Introducing a dummy sort so that we retrieve all the data, sort it and then sequentially visit these data blocks.

Case 2 – Rollback Transaction Slot Overwritten
这种问题，主要是延迟块清理导致，一般建议在进行大批量的dml操作后，使用全表(全index)扫描执行一遍，或者收集全部统计信息

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恢复被rm意外删除数据文件

发表于 2011 年 12 月 31 日 由 惜分飞

一.模拟数据文件删除

[oracle@node1 ~]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.3.0 Production on Sat Dec 31 22:00:52 2011

Copyright (c) 1982, 2011, Oracle.  All rights reserved.

--数据库版本
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
With the Partitioning, Oracle Label Security, OLAP, Data Mining,
Oracle Database Vault and Real Application Testing options

--所有数据文件
SQL> select name from v$datafile;

NAME
--------------------------------------------------------------------------------
/opt/oracle/oradata/ora11g/system01.dbf
/opt/oracle/oradata/ora11g/sysaux01.dbf
/opt/oracle/oradata/ora11g/undotbs01.dbf
/opt/oracle/oradata/ora11g/users01.dbf
/opt/oracle/oradata/ora11g/example01.dbf

--删除example01.dbf数据文件
SQL> !rm /opt/oracle/oradata/ora11g/example01.dbf

SQL> !ls -l /opt/oracle/oradata/ora11g/example01.dbf
ls: /opt/oracle/oradata/ora11g/example01.dbf: 没有那个文件或目录

--因为数据文件被删除，创建表失败
SQL> create table t_xifenfei tablespace example
  2  as select * from dba_tables;
as select * from dba_tables
                 *
ERROR at line 2:
ORA-01116: error in opening database file 5
ORA-01110: data file 5: '/opt/oracle/oradata/ora11g/example01.dbf'
ORA-27041: unable to open file
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3

二.找回数据文件

--查找dbw进程spid
[oracle@node1 ~]$ ps -ef|grep dbw|grep -v grep
oracle   18387     1  0 Dec22 ?        00:00:12 ora_dbw0_ora11g

--查看该进程所有文件句柄
[oracle@node1 ~]$ ll /proc/18387/fd
总计 0
lr-x------ 1 oracle oinstall 64 12-31 22:03 0 -> /dev/null
l-wx------ 1 oracle oinstall 64 12-31 22:03 1 -> /dev/null
lr-x------ 1 oracle oinstall 64 12-31 22:03 10 -> /dev/zero
lr-x------ 1 oracle oinstall 64 12-31 22:03 11 -> /dev/zero
lr-x------ 1 oracle oinstall 64 12-31 22:03 12 -> /opt/oracle/product/11.2.0/db_1/rdbms/mesg/orazhs.msb
lrwx------ 1 oracle oinstall 64 12-31 22:03 13 -> /opt/oracle/product/11.2.0/db_1/dbs/hc_ora11g.dat
lr-x------ 1 oracle oinstall 64 12-31 22:03 14 -> /proc/18387/fd
lr-x------ 1 oracle oinstall 64 12-31 22:03 15 -> /dev/zero
lr-x------ 1 oracle oinstall 64 12-31 22:03 16 -> /opt/oracle/product/11.2.0/db_1/rdbms/mesg/oraus.msb
lrwx------ 1 oracle oinstall 64 12-31 22:03 17 -> /opt/oracle/product/11.2.0/db_1/dbs/hc_ora11g.dat
lrwx------ 1 oracle oinstall 64 12-31 22:03 18 -> /opt/oracle/product/11.2.0/db_1/dbs/lkORA11G
lr-x------ 1 oracle oinstall 64 12-31 22:03 19 -> /opt/oracle/product/11.2.0/db_1/rdbms/mesg/orazhs.msb
l-wx------ 1 oracle oinstall 64 12-31 22:03 2 -> /dev/null
lr-x------ 1 oracle oinstall 64 12-31 22:03 20 -> /opt/oracle/product/11.2.0/db_1/rdbms/mesg/oraus.msb
lrwx------ 1 oracle oinstall 64 12-31 22:03 21 -> socket:[441562]
lrwx------ 1 oracle oinstall 64 12-31 22:03 256 -> /opt/oracle/oradata/ora11g/control01.ctl
lrwx------ 1 oracle oinstall 64 12-31 22:03 257 -> /opt/oracle/oradata/ora11g/system01.dbf
lrwx------ 1 oracle oinstall 64 12-31 22:03 258 -> /opt/oracle/oradata/ora11g/sysaux01.dbf
lrwx------ 1 oracle oinstall 64 12-31 22:03 259 -> /opt/oracle/oradata/ora11g/undotbs01.dbf
lrwx------ 1 oracle oinstall 64 12-31 22:03 260 -> /opt/oracle/oradata/ora11g/users01.dbf
lrwx------ 1 oracle oinstall 64 12-31 22:03 261 -> /opt/oracle/oradata/ora11g/example01.dbf (deleted)
lrwx------ 1 oracle oinstall 64 12-31 22:03 262 -> /opt/oracle/oradata/ora11g/temp01.dbf
lr-x------ 1 oracle oinstall 64 12-31 22:03 3 -> /dev/null
lr-x------ 1 oracle oinstall 64 12-31 22:03 4 -> /dev/null
lrwx------ 1 oracle oinstall 64 12-31 22:03 5 -> /opt/oracle/product/11.2.0/db_1/dbs/hc_ora11g.dat
lr-x------ 1 oracle oinstall 64 12-31 22:03 6 -> /dev/null
lr-x------ 1 oracle oinstall 64 12-31 22:03 7 -> /dev/null
lr-x------ 1 oracle oinstall 64 12-31 22:03 8 -> /dev/null
lr-x------ 1 oracle oinstall 64 12-31 22:03 9 -> /dev/null
--通过句柄恢复数据文件[被删除数据文件会被标示(deleted)]
[oracle@node1 ~]$ cp /proc/18387/fd/261 /opt/oracle/oradata/ora11g/example01.dbf
--确认该数据文件已经恢复成功
[oracle@node1 ~]$ ll /opt/oracle/oradata/ora11g/example01.dbf
-rw-r----- 1 oracle oinstall 362422272 12-31 22:05 /opt/oracle/oradata/ora11g/example01.dbf

三.数据文件online

SQL> alter database datafile 5 offline;
 
Database altered.
 
SQL> recover datafile 5;
Media recovery complete.
SQL> alter database datafile 5 online;
 
Database altered.

SQL> create table t_xifenfei tablespace example
  2  as select * from dba_tables;

Table created.

四.补充说明
在意外使用os命令删除掉数据文件时，千万不要慌张重启数据库或者操作系统，可以通过dbwn进程相关句柄找回数据文件

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在UltraEdit中定位数据文件内容

发表于 2011 年 12 月 30 日 由 惜分飞

一、定位数据块
1.bbed查看数据块

--第一个数据块
BBED> set block 1
        BLOCK#          1
BBED> dump count 16
 File: /opt/oracle/oradata/chf/example01.dbf (0)
 Block: 1                Offsets:    0 to   15           Dba:0x00000000
------------------------------------------------------------------------
 0ba20000 01004001 00000000 00000104 

 <32 bytes per line>

BBED> dump count 128
 File: /opt/oracle/oradata/chf/example01.dbf (0)
 Block: 1                Offsets:    0 to  127           Dba:0x00000000
------------------------------------------------------------------------
 0ba20000 01004001 00000000 00000104 387a0000 00000000 0003200b 74684acd 
 43484600 00000000 7d4a0000 00320000 00200000 05000300 00000000 00000000 
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 
 00000000 d28a0900 00000000 1ab5d72c f7b4d72c c5320900 00000000 00000000 

 <32 bytes per line>

--第二个数据块

BBED> set block 2
        BLOCK#          2

BBED> dump count 128
 File: /opt/oracle/oradata/chf/example01.dbf (0)
 Block: 2                Offsets:    0 to  127           Dba:0x00000000
------------------------------------------------------------------------
 1da20000 02004001 08dee400 00000204 f6b80000 05000000 08000000 00320000 
 09000000 50000000 feff3f00 07000000 00320000 7f000000 fa010000 07dee400 
 00000000 00000000 00000000 00000000 b1220000 08000000 00000000 00000000 
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 

 <32 bytes per line>

--第100个数据块
BBED> set block 100
        BLOCK#          100

BBED> dump count 128
 File: /opt/oracle/oradata/chf/example01.dbf (0)
 Block: 100              Offsets:    0 to  127           Dba:0x00000000
------------------------------------------------------------------------
 06a20000 64004001 343f0900 00000104 a38d0000 02002000 e1c90000 343f0900 
 0000e81f 021f3200 61004001 00000000 00000000 00000000 00000000 00000000 
 00000000 05000900 2c010000 52008000 c8005900 00800000 a3350900 00000000 
 00000000 00008001 00000000 6b00fa00 5e1a6419 00000000 00000000 00000000 

 <32 bytes per line>

2.UltraEdit查看数据块

--第0个数据块
--(为了便于和bbed的block一致，称为0比较合适，因为这个块在bbed中看不到)
00000000h: 00 A2 00 00 00 00 C0 FF 00 00 00 00 00 00 00 00 ; .?...?........
00000010h: 66 C8 00 00 00 20 00 00 00 32 00 00 7D 7C 7B 7A ; f?.. ...2..}|{z
00000020h: A0 81 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ; 爜..............
00000030h: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ; ................
……………………………………………………
00001fa0h: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ; ................
00001fb0h: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ; ................
00001fc0h: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ; ................
00001fd0h: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ; ................
00001fe0h: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ; ................
00001ff0h: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ; ................  
--第一个数据块（bbed中的block 1）
00002000h: 0B A2 00 00 01 00 40 01 00 00 00 00 00 00 01 04 ; .?...@.........
00002010h: 38 7A 00 00 00 00 00 00 00 03 20 0B 74 68 4A CD ; 8z........ .thJ?
……………………………………………………………
000021c0h: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ; ................
000021d0h: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ; ................
--第二个数据块(bbed中的block 2)
00004000h: 1D A2 00 00 02 00 40 01 08 DE E4 00 00 00 02 04 ; .?...@..掬.....
00004010h: F6 B8 00 00 05 00 00 00 08 00 00 00 00 32 00 00 ; 龈...........2..
00004020h: 09 00 00 00 50 00 00 00 FE FF 3F 00 07 00 00 00 ; ....P...??.....
00004030h: 00 32 00 00 7F 00 00 00 FA 01 00 00 07 DE E4 00 ; .2.....?...掬.
00004040h: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ; ................
--第100个数据块(bbed中的block 100)
000c8000h: 06 A2 00 00 64 00 40 01 34 3F 09 00 00 00 01 04 ; .?.d.@.4?......
000c8010h: A3 8D 00 00 02 00 20 00 E1 C9 00 00 34 3F 09 00 ; .... .嵘..4?..
000c8020h: 00 00 E8 1F 02 1F 32 00 61 00 40 01 00 00 00 00 ; ..?..2.a.@.....
000c8030h: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ; ................
000c8040h: 00 00 00 00 05 00 09 00 2C 01 00 00 52 00 80 00 ; ........,...R.€.
000c8050h: C8 00 59 00 00 80 00 00 A3 35 09 00 00 00 00 00 ; ?Y..€..?......
000c8060h: 00 00 00 00 00 00 80 01 00 00 00 00 6B 00 FA 00 ; ......€.....k.?
000c8070h: 5E 1A 64 19 00 00 00 00 00 00 00 00 00 00 00 00 ; ^.d.............

3.结论:因为2000(16进制)=8192(10进制),而每行又是16，所以UltraEdit定位块的规则是
SELECT to_char(’2*块数’,’xxxxxxx’) xff FROM dual;(xff*1000)

SQL> SELECT TO_number('2000','xxxxxx') FROM dual;

TO_NUMBER('2000','XXXXXX')
--------------------------
                      8192

二、UltraEdit定位块内内容
1.bbed查看内容

--第一块偏移量为484数据
BBED> set block 1
        BLOCK#          1

BBED> set offset 484
        OFFSET          484

BBED> dump count 128
 File: /opt/oracle/oradata/chf/example01.dbf (0)
 Block: 1                Offsets:  484 to  611           Dba:0x00000000
------------------------------------------------------------------------
 c052e700 00000000 ec82ba2d 01000000 2e060000 39020000 10008984 02000000 
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 

 <32 bytes per line>

--第一块偏移量为8188数据
BBED> dump offset 8188 count 128
 File: /opt/oracle/oradata/chf/example01.dbf (0)
 Block: 1                Offsets: 8188 to 8191           Dba:0x00000000
------------------------------------------------------------------------
 010b0000 

 <32 bytes per line>

2.UltraEdit中内容

--offset 484(kscnbas)
000021e0h: 00 00 00 00 C0 52 E7 00 00 00 00 00 EC 82 BA 2D ; ....繰?....靷?    
000021f0h: 01 00 00 00 2E 06 00 00 39 02 00 00 10 00 89 84 ; ........9.....墑
00002200h: 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ; ................

--offset 8188(tailchk) 
00003ff0h: 00 00 00 00 00 00 00 00 00 00 00 00 01 0B 00 00 ; ................

3.结论:10进制的便宜量转换为16进制，然后对照你块开始行号+偏移量(16进制),得到对应偏移量开始位置

SQL> SELECT to_char('484','xxxxxxx') FROM dual;

TO_CHAR('484','X
----------------
     1e4

SQL> SELECT to_char('8188','xxxxxxx') FROM dual;

TO_CHAR('8188','
----------------
    1ffc

三.补充说明
1.本实验是拷贝linux下11g数据文件到win上使用UltraEdit操作得出
2.使用UltraEdit,需要熟悉对一些关键数据的偏移量比较清楚

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