Oracle Database open error ORA-01555: snapshot too old.

During his honeymoon in Dongguan today, a student said that the test library he managed had a problem and could not be opened. Let's first look at the problem:
Recovery of Online Redo Log: Thread 1 Group 4 Seq 4 Reading mem 0
Mem #0:/onlinelog/shr/redo04.log
Completed redo application of 0.00 MB
Completed crash recovery
Thread 1: logseq 4, block 3, scn 7755957
0 data blocks read, 0 data blocks written, 0 redo k-bytes read
Thread 1 advanced to log sequence 5 (thread open)
Thread 1 opened at log sequence 5
Current log #5 seq #5 mem #0:/onlinelog/shr/redo05.log
Successful open of redo thread 1
MTTR advisory is disabled because FAST_START_MTTR_TARGET is not set
Thu Jun 19 13:31:35 2014
SMON: enabling cache recovery
ORA-01555 caused by SQL statement below (SQL ID: 4krwuz0ctqxdt, SCN: 0x0000. 007658ba ):
Select ctime, mtime, stime from obj $ where obj # =: 1
Errors in file/oracle/diag/rdbms/shr/trace/shr_ora_5262.trc:
ORA-00704: bootstrap process failure.
ORA-00704: bootstrap process failure.
ORA-00604: error occurred at recursive SQL level 1
ORA-01555: snapshot too old: rollback segment number 6 with name "_ SYSSMU6_1263032392 $" too small
Errors in file/oracle/diag/rdbms/shr/trace/shr_ora_5262.trc:
ORA-00704: bootstrap process failure.
ORA-00704: bootstrap process failure.
ORA-00604: error occurred at recursive SQL level 1
ORA-01555: snapshot too old: rollback segment number 6 with name "_ SYSSMU6_1263032392 $" too small
Error 704 happened during db open, shutting down database
USER (ospid: 5262): terminating the instance due to error 704
Instance terminated by USER, pid = 5262
ORA-1092 signalled during: alter database open...
Opiodr aborting process unknown ospid (5262) as a result of ORA-1092
Thu Jun 19 13:31:37 2014
ORA-1092: opitsk aborting process
From the above error, the reason why the database fails to open is that Oracle encountered a ora-01555 error when executing recursive SQL in the bootstrap stage,
In this way, the bootstrap process cannot continue, and the database cannot be opened. We can see that the error SQL statement is as follows:
Select ctime, mtime, stime from obj $ where obj # =: 1
This is a very familiar SQL statement. You will find this SQL statement when tracking Oracle open through 10046 trace.
For this error, some people may think it is a rollback segment problem. In fact, it is not. In this case, the SCN can smoothly open the database.
But there is a problem here: the brother's database is Oracle 11.2.0.4 and does not support the traditional 10015 event method.
Here we solve this problem through oradebug:
SQL & gt; conn/as sysdba
Connected to an idle instance.
SQL & gt; startup mount
ORACLE instance started.
 
Total System Global Area 4275781632 bytes
Fixed Size 2260088 bytes
Variable Size 989856648 bytes
Database Buffers 3271557120 bytes
Redo Buffers 12107776 bytes
Database mounted.
SQL & gt;
SQL & gt; oradebug poke 0x06001AE70 4 0x859AFA
ORA-00074: no process has been specified
SQL & gt; oradebug setmypid
Statement processed.
SQL & gt; oradebug DUMPvar SGA kcsgscn _
Kcslf kcsgscn _ [06001AE70, 06001AEA0) = 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 6001AB50 00000000
SQL & gt; oradebug poke 0x06001AE70 4 0x859AFA
BEFORE: [06001AE70, 06001AE74) = 00000000
AFTER: [06001AE70, 06001AE74) = 00859AFA
SQL & gt; alter database open;
 
Database altered.
 
SQL & gt;
Here, we will briefly explain that 4 is the length, and 0x859AFA is in hexadecimal notation. Based on the original v $ datafile_header.checkpoint_change #,
Add up to 1000000 to get this value.
We can see that the database is successfully opened. Finally, observe alert log found that there is a ora-00600 4194 error.
Thu Jun 19 14:48:43 2014
Dumping diagnostic data in directory = [cdmp_20140619144843], requested by (instance = 1, osid = 9140 (MMON), summary = [incident = 132122].
Exception [type: SIGSEGV, Address not mapped to object] [ADDR: 0x3D6C3836] [PC: 0x97F4DF6, kgegpa () + 40] [flags: 0x0, count: 1]
Exception [type: SIGSEGV, Address not mapped to object] [ADDR: 0x3D6C3836] [PC: 0x97f0000a, kgebse () + 776] [flags: 0x2, count: 2]
Thu Jun 19 14:48:46 2014
Flush retried for xcb 0x159c668c8, pmd 0x15870d270
Errors in file/oracle/diag/rdbms/shr/trace/shr_pmon_9112.trc (incident = 132017 ):
ORA-00600: internal error code, arguments: [4194], [], [], [], [], [], [], [], [], [], [], []
Incident details in:/oracle/diag/rdbms/shr/incident/incdir_132017/shr_pmon_91__i132017.trc
Use ADRCI or Support Workbench to package the incident.
See Note 411.1 at My Oracle Support for error and packaging details.
Thu Jun 19 14:48:47 2014
Errors in file/oracle/diag/rdbms/shr/trace/shr_ora_9268.trc (incident = 132209 ):
ORA-00600: internal error code, arguments: [4194], [], [], [], [], [], [], [], [], [], [], []
ORA-00001: unique constraint (SYSTEM. UNQ_PAIRS) violated
Incident details in:/oracle/diag/rdbms/shr/incident/incdir_132209/shr_ora_9268_i132209.trc
Use ADRCI or Support Workbench to package the incident.
See Note 411.1 at My Oracle Support for error and packaging details.
Errors in file/oracle/diag/rdbms/shr/trace/shr_pmon_9112.trc:
ORA-00600: internal error code, arguments: [4194], [], [], [], [], [], [], [], [], [], [], []
PMON (ospid: 9112): terminating the instance due to error 472
System state dump requested by (instance = 1, osid = 9112 (PMON), summary = [abnormal instance termination].
System State dumped to trace file/oracle/diag/rdbms/shr/trace/shr_diag_9122_20140619144848.trc
Dumping diagnostic data in directory = [cdmp_20140619144848], requested by (instance = 1, osid = 9112 (PMON), summary = [abnormal instance termination].
Instance terminated by PMON, pid = 9112
This is a very common error. The simplest method is to reconstruct the undo or process the rollback segment. Here we use the simplest method:
Modify undo_management = manual
Undo_tablespace = 'system'
SQL & gt; l
1 * create pfile = '/tmp/1. ora' from spfile
SQL & gt; startup mount pfile = '/tmp/1. ora ';
ORACLE instance started.
 
Total System Global Area 4275781632 bytes
Fixed Size 2260088 bytes
Variable Size 989856648 bytes
Database Buffers 3271557120 bytes
Redo Buffers 12107776 bytes
Database mounted.
SQL & gt; alter database open;
 
Database altered.
 
SQL & gt; select name from v $ datafile;
 
NAME
--------------------------------------------------------------------------------
/Oracle/oradata/shr/system01.dbf
/Oracle/oradata/shr/sysaux01.dbf
/Oracle/oradata/shr/undotbs01.dbf
/Oracle/oradata/shr/users01.dbf
/Oradata/shr/jy_shr01.dbf
/Oradata/shr/jy_shr02.dbf
/Oradata/shr/jy_shr03.dbf
/Oradata/shr/eas_d_stand01.dbf
/Oradata/shr/eas_d_stand02.dbf
/Oradata/shr/eas_d_stand03.dbf
/Backup/eas/eas_d_stand04.dbf
 
NAME
--------------------------------------------------------------------------------
/Backup/eas/eas_d_stand05.dbf
/Backup/eas/eas_d_stand06.dbf
 
13 rows selected.
 
SQL & gt; show parameter undo
 
NAME TYPE VALUE
-----------------------------------------------------------------------------
Undo_management string MANUAL
Undo_retention integer 900
Undo_tablespace string SYSTEM
SQL & gt; create undo tablespace undotbs2 datafile '/oracle/oradata/shr/undotbs2_01.dbf' size 200 m;
 
Tablespace created.
 
SQL & gt; shutdown immediate
After undo is rebuilt, stop the database and modify the undo parameter to open the database as follows:
SQL & gt; create spfile from pfile = '/tmp/1. ora ';
 
File created.
 
SQL & gt; startup mount
ORACLE instance started.
 
Total System Global Area 4275781632 bytes
Fixed Size 2260088 bytes
Variable Size 989856648 bytes
Database Buffers 3271557120 bytes
Redo Buffers 12107776 bytes
Database mounted.
SQL & gt; alter database open;
 
Database altered.
 
SQL & gt;
 
After processing, alert log will not throw any errors.