Monday, April 18, 2011

How to Determine the Name of the Trace File to be Generated


In many cases we need to find out the name of the latest trace file generated in the USER_DUMP_DEST directory. What we usually do is, that we physically go to the USER_DUMP_DEST location with the operating system browser and sort all the files by date and look for latest files. We can remove this hassle easily if we know what would be the trace file name in advance. Let's have a look ...

Demo : 1 
C:\>sqlplus sys/xxxx@noida as sysdba
SQL*Plus: Release 11.1.0.6.0 - Production on Mon Apr 18 17:44:49 2011
Copyright (c) 1982, 2007, Oracle.  All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> alter database backup controlfile to trace;
Database altered.

The above Command will generate the trace file inside USER_DUMP_DEST. Let's check the location of USER_DUMP_DESTIf we are using Sql*plus then issue,

SQL> show parameter user_dump_dest
NAME                         TYPE           VALUE
--------------                --------     -----------------------------------------------------
user_dump_dest        string       d:\oracle\diag\rdbms\noida\noida\trace

Here the latest files are for latest trace . Sometimes, we may not get the right trace file .Now it would be quite easy task if we knew the name of the trace file to be generated by ALTER DATABASE command. In advance we can get the trace file name as 

SQL> SELECT s.sid, s.serial#, pa.value || '\' || LOWER(SYS_CONTEXT('userenv','instance_name')) ||
          '_ora_' || p.spid || '.trc'  AS trace_file        FROM   v$session s,  v$process p, v$parameter pa
   WHERE  pa.name = 'user_dump_dest'     AND    s.paddr = p.addr
   AND    s.audsid = SYS_CONTEXT('USERENV', 'SESSIONID');
   SID            SERIAL#                     TRACE_FILE
---------        ----------           -----------------------------------------------------------------------
 110             312                  d:\oracle\diag\rdbms\noida\noida\trace\noida_ora_3552.trc
  
the trace file to be generated now will be named as noida_ora_3552.trc . So now issuing, "alter database backup controlfile to trace" will generate the file named d:\oracle\diag\rdbms\noida\noida\trace\noida_ora_3552.trc

Demo : 2 
This method is much simple and easy to identify the trace file. Let's have a look on another demo .

C:\>sqlplus sys/xxxx@noida as sysdba
SQL*Plus: Release 11.1.0.6.0 - Production on Mon Apr 18 17:49:49 2011
Copyright (c) 1982, 2007, Oracle.  All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> show   parameter    user_dump_dest
NAME                             TYPE                    VALUE
---------------------           --------       ----------------------------------------
user_dump_dest          string           d:\oracle\diag\rdbms\noida\noida\trace

SQL> alter session set tracefile_identifier='mytracefile' ;
Session altered.
SQL>  alter database backup controlfile to trace; 
Session altered.


Now, go to the user_dump_dest location and find the trace file having name "mytracefile" . In mycase the name is   "noida_ora_3552_mytracefile.trc"

The difference between the two demo is that first demo is on system level so it will give all the trace file generated by different session whereas in second case , it will show  the trace file for particular session only . The another difference between is that in first demo we have to fire the command and then check the tracefile but in second demo we have to set the trace file name so that we can easily identify the correct trace file .


Enjoy      :-)


Saturday, April 16, 2011

How To Determine the DBID ?

The DBID is a unique identifier. It is found in all datafile headers. The DBID is used to identifiy the database a file belongs to.  There may be situations where we need the recovery of the spfile or control file from autobackup, such as disaster recovery when we have lost all database files , then in such case  we will need  to determine the DBID to restore the database . If we do not have a record of the DBID of database, there are two places from where we can easily find it.

1.) The DBID is used in forming the filename for the control file autobackup. Below is the name of my autobackup controlfile name    ==  C-1502483083-20110416-00

Here 1502483083 specifies  the DBID   and 20110416  specifies the date i.e, 16th april 2011

2.) If we have any text files that preserve the output from an RMAN session, the DBID is displayed by the RMAN client when it starts up and connects to your database. Typical output follows:


C:\>rman target sys/xxxx@noida
Recovery Manager: Release 11.1.0.6.0 - Production on Sat Apr 16 17:23:28 2011
Copyright (c) 1982, 2007, Oracle.  All rights reserved.
connected to target database: NOIDA (DBID=1502483083)


Enjoy      J J J


Flashback_Scn and flashback_Time parameter of Data Pump

Flashback_Scn  and  flashback_Time  are  two  important  feature  of  the  datapump 11g . If  we  want  to  run  a  large  export  whilst  the  database  is  in  use  then  ideally  we  should  always use  one  of  the  two  flashback  parameters. The export  operation  is  performed  with  data  that is  consistent  as  of  the  specified  SCN .  FLASHBACK_SCN and FLASHBACK_TIME are mutually exclusive .

FLASHBACK_TIME : The SCN that most closely matches the specified time is found, and this SCN is used to enable the Flashback utility. The export operation is performed with data that is consistent as of this SCN. The FLASHBACK_SCN parameter pertains only to the Flashback Query capability of Oracle Database. It is not applicable to Flashback Database, Flashback Drop, or Flashback Data Archive. We can get the scn number from the following query :

SQL> select current_scn from v$database ;       or
SQL>select dbms_flashback.get_system_change_number from dual ; 

Let's have a Demo of the flashback_scn

SQL> select current_scn from v$database;
CURRENT_SCN
-----------
    1140271

SQL> create table hr.test as select * from test;
Table created.
SQL> select current_scn from v$database;
CURRENT_SCN
-----------
    1140487
Let's take a export using flashback_scn  parameter

C:\>expdp system/ramtech@noida directory=dpump schemas=hr dumpfile=flashback_hr.dmp logfile=flashlog.log       flashback_scn=1140271
Export: Release 11.1.0.6.0 - Production on Saturday, 16 April, 2011 11:35:45
Copyright (c) 2003, 2007, Oracle.  All rights reserved.
Connected to: Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
Starting "SYSTEM"."SYS_EXPORT_SCHEMA_01":  system/********@noida directory=dpump schemas=hr dumpfile=flashback_hr.dmp logfile=flashlog.log    flashback_scn=1140271
Estimate in progress using BLOCKS method...
Processing object type SCHEMA_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 512 KB
Processing object type SCHEMA_EXPORT/USER
Processing object type SCHEMA_EXPORT/SYSTEM_GRANT
Processing object type SCHEMA_EXPORT/ROLE_GRANT
Processing object type SCHEMA_EXPORT/DEFAULT_ROLE
Processing object type SCHEMA_EXPORT/PRE_SCHEMA/PROCACT_SCHEMA
Processing object type SCHEMA_EXPORT/SEQUENCE/SEQUENCE
Processing object type SCHEMA_EXPORT/TABLE/TABLE
Processing object type SCHEMA_EXPORT/TABLE/GRANT/OWNER_GRANT/OBJECT_GRANT
Processing object type SCHEMA_EXPORT/TABLE/INDEX/INDEX
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/CONSTRAINT
Processing object type SCHEMA_EXPORT/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Processing object type SCHEMA_EXPORT/TABLE/COMMENT
Processing object type SCHEMA_EXPORT/PROCEDURE/PROCEDURE
Processing object type SCHEMA_EXPORT/PROCEDURE/ALTER_PROCEDURE
Processing object type SCHEMA_EXPORT/VIEW/VIEW
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/REF_CONSTRAINT
Processing object type SCHEMA_EXPORT/TABLE/TRIGGER
Processing object type SCHEMA_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
Processing object type SCHEMA_EXPORT/POST_SCHEMA/PROCACT_SCHEMA
. . exported "HR"."COUNTRIES"                            6.375 KB      25 rows
. . exported "HR"."DEPARTMENTS"                          7.015 KB      27 rows
. . exported "HR"."EMPLOYEES"                            16.80 KB     107 rows
. . exported "HR"."JOBS"                                 6.984 KB      19 rows
. . exported "HR"."JOB_HISTORY"                          7.054 KB      10 rows
. . exported "HR"."LOCATIONS"                            8.273 KB      23 rows
. . exported "HR"."REGIONS"                              5.484 KB       4 rows
ORA-31693: Table data object "HR"."TEST" failed to load/unload and is being skipped due to error:
ORA-02354: error in exporting/importing data
ORA-01466: unable to read data - table definition has changed
Master table "SYSTEM"."SYS_EXPORT_SCHEMA_01" successfully loaded/unloaded
******************************************************************************
Dump file set for SYSTEM.SYS_EXPORT_SCHEMA_01 is:
  D:\DPUMP\FLASHBACK_HR.DMP
Job "SYSTEM"."SYS_EXPORT_SCHEMA_01" completed with 1 error(s) at 11:37:50

The above error show that the table "test"  is not include in the  export operation because the SCN mention  is of before the table "test" creation. The below export will show the export upto current SCN when database is in use.

C:\>expdp system/ramtech@noida directory=dpump schemas=hr dumpfile=flashback_hr1.dmp  logfile=flashback_log.log
Export: Release 11.1.0.6.0 - Production on Saturday, 16 April, 2011 11:44:50
Copyright (c) 2003, 2007, Oracle.  All rights reserved.
Connected to: Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
Starting "SYSTEM"."SYS_EXPORT_SCHEMA_01":  system/********@noida directory=dpump schemas=hr dumpfile=flashback_hr1.dmp logfile=flashback_log.log
Estimate in progress using BLOCKS method...
Processing object type SCHEMA_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 512 KB
Processing object type SCHEMA_EXPORT/USER
Processing object type SCHEMA_EXPORT/SYSTEM_GRANT
Processing object type SCHEMA_EXPORT/ROLE_GRANT
Processing object type SCHEMA_EXPORT/DEFAULT_ROLE
Processing object type SCHEMA_EXPORT/PRE_SCHEMA/PROCACT_SCHEMA
Processing object type SCHEMA_EXPORT/SEQUENCE/SEQUENCE
Processing object type SCHEMA_EXPORT/TABLE/TABLE
Processing object type SCHEMA_EXPORT/TABLE/GRANT/OWNER_GRANT/OBJECT_GRANT
Processing object type SCHEMA_EXPORT/TABLE/INDEX/INDEX
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/CONSTRAINT
Processing object type SCHEMA_EXPORT/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Processing object type SCHEMA_EXPORT/TABLE/COMMENT
Processing object type SCHEMA_EXPORT/PROCEDURE/PROCEDURE
Processing object type SCHEMA_EXPORT/PROCEDURE/ALTER_PROCEDURE
Processing object type SCHEMA_EXPORT/VIEW/VIEW
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/REF_CONSTRAINT
Processing object type SCHEMA_EXPORT/TABLE/TRIGGER
Processing object type SCHEMA_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
Processing object type SCHEMA_EXPORT/POST_SCHEMA/PROCACT_SCHEMA
. . exported "HR"."COUNTRIES"                                6.375 KB      25 rows
. . exported "HR"."DEPARTMENTS"                          7.015 KB      27 rows
. . exported "HR"."EMPLOYEES"                             16.80 KB     107 rows
. . exported "HR"."JOBS"                                             6.984 KB      19 rows
. . exported "HR"."JOB_HISTORY"                             7.054 KB      10 rows
. . exported "HR"."LOCATIONS"                                8.273 KB      23 rows
. . exported "HR"."REGIONS"                                      5.484 KB       4 rows
. . exported "HR"."TEST"                                              5.054 KB       8 rows
Master table "SYSTEM"."SYS_EXPORT_SCHEMA_01" successfully loaded/unloaded
******************************************************************************
Dump file set for SYSTEM.SYS_EXPORT_SCHEMA_01 is:
  D:\DPUMP\FLASHBACK_HR1.DMP
Job "SYSTEM"."SYS_EXPORT_SCHEMA_01" successfully completed at 11:46:41


Enjoy     :-)