REDO LOG FILE

Redo log files are filled with redo records. A redo record also called a redo entry, is made up of a group of change vectors, each of which is a description of a change made to a single block in the database. For example, if you change a salary value in an employee table, you generate a redo record containing change vectors that describe changes to the data segment block for the table, the undo segment data block, and the transaction table of the undo segments.

Redo entries record data that you can use to reconstruct all changes made to the database, including the undo segments. Therefore, the redo log also protects rollback data. When you recover the database using redo data, the database reads the change vectors in the redo records and applies the changes to the relevant blocks.

SQL> select * from v$log;

SQL> select group#,status,sequence# from v$log;

    GROUP# STATUS            SEQUENCE#
---------- ---------------- ----------
         1 CURRENT                  91
         2 INACTIVE                 89
         3 INACTIVE                 90
SQL> select * from v$logfile;

Active (Current) and Inactive Redo Log Files

Oracle Database uses only one redo log file at a time to store redo records written from the redo log buffer. The redo log file that LGWR is actively writing to is called the current redo log file.

Redo log files that are required for instance recovery are called active redo log files. Redo log files that are no longer required for instance recovery are called inactive redo log files.

If you have enabled archiving (the database is in ARCHIVELOG mode), then the database cannot reuse or overwrite an active online log file until one of the archiver background processes (ARCn) has archived its contents. If archiving is disabled (the database is in NOARCHIVELOG mode), then when the last redo log file is full, LGWR continues by overwriting the first available active file.

Add New redo log file

SQL> alter database add logfile group 4 '/u01/app/oracle/oradata/TESTDB/redo04.dbf' 
size 100m; Database altered.

Add Member to an existing group

SQL> alter database add logfile member '/u01/app/oracle/oradata/TESTDB/redo04b.log' 
to group 4; Database altered.

Drop member

SQL> alter database drop logfile member '/u01/app/oracle/oradata/TESTDB/redo04b.log';

Database altered.

Drop Logfile Group

SQL> alter database drop logfile group 4;

Database altered.


SQL> select group#,status from v$log;

    GROUP#                STATUS
----------            ----------------
         1               CURRENT
         2               INACTIVE
         3               INACTIVE

Adding Two  member

SQL> alter database add logfile group 4 ('/u01/app/oracle/oradata/TESTDB/redo04a.log',
'/u01/app/oracle/oradata/TESTDB/redo04C.log') size 100m; Database altered.
SQL> select group#,member from v$logfile;

    GROUP#         MEMBER
----------       ---------------------------                       
         4    /u01/app/oracle/oradata/TESTDB/redo04a.log

         4     /u01/app/oracle/oradata/TESTDB/redo04C.log

Log Switches and Log Sequence Numbers

A log switch is a point at which the database stops writing to one redo log file and begins writing to another. Normally, a log switch occurs when the current redo log file is completely filled and writing must continue to the next redo log file. However, you can configure log switches to occur at regular intervals, regardless of whether the current redo log file is completely filled. You can also force log switches manually.

Oracle Database assigns each redo log file a new log sequence number every time a log switch occurs and LGWR begins writing to it. When the database archives redo log files, the archived log retains its log sequence number. A redo log file that is cycled back for use is given the next available log sequence number.

Each online or archived redo log file is uniquely identified by its log sequence number. During a crash, instance, or media recovery, the database properly applies to redo log files in ascending order by using the log sequence number of the necessary archived and redo log files.

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Oracle 12c to 19c upgrade using AutoUpgrade Method

In this blog, we will see how to upgrade Oracle Database 12c to 19c using AutoUpgrade Tool

What is the AutoUpgrade?

  • The Oracle Database AutoUpgrade utility is a small command-line tool that allows you to upgrade your databases very easily with very little interaction
  • The new AutoUpgrade utility in Oracle 19¢ performs almost 99% of the task by itself, we just have to provide inputs during the initial phase
  • So it performs Prechecks against multiple databases, upgrades multiple databases in one go
  • Also, it does Post upgrade, object recompilation, and time zone up-gradation
  • The only thing you need to provide is a contig file in text format

Which database releases are supported?

  • As a source, the minimum version is Oracle Database 11.2.0.4. onwards

Download the latest auto-upgrade jar file

  • Auto upgrade utility autoupgrade.jar file exists by default under $ORACLE_HOME/rdbms/admin directory of Oracle 19c Home
  • Oracle strongly recommends downloading the latest AutoUpgrade version before doing the upgrade
  • You download the most recent version from MOS Note: 2485487.1  AutoUpgrade Tool
  • Once you download this jar file transfer it to the Server and create a new directory and place this file in that directory

cp -r autoupgrade.jar /u01/app/oracle/product/19.0.0/db_1/rdbms/admin/

Java version:

  • Java version should be 8 or later, which is available by default in Oracle Database homes from release 12.1.0.2 and latest

Create the config file

  • Create New Directory Which will contain your config file and logs
  • mkdir /home/oracle/auto_upgrade_19c

Run Below command to create sample config file which we will use to make final config file.

  • cd /home/oracle/auto_upgrade_19c
  • $ORACLE_HOME/jdk/bin/java -jar $ORACLE_HOME/rdbms/admin/autoupgrade.jar -create_sample_file_config
  • cp sample_config.cfg prod_db_config.cfg
  • Make necessary changes

Modify the config file according to your env

prddb_config.cfg file should have following entry which specifies source and target database home location and DB name and log locations and other information’s:

global.autoupg_log_dir=/home/oracle/auto_upgrade_19c/upg_logs
upg1.dbname=PRDDB
upg1.start_time=NOW
upg1.source_home=/u01/app/oracle/product/12.2.0.1/db_1
upg1.target_home=/u01/app/oracle/product/19.0.0/db_1
upg1.sid=PRDDB
upg1.log_dir=/home/oracle/auto_upgrade_19c/upg_logs/PRDDB
upg1.upgrade_node=orclagent.localdomain
upg1.target_version=19.12
upg1.run_utlrp=yes
upg1.timezone_upg=yes

Analyze the database using modified config file

Auto upgrade Analyze mode checks your database to see if it is ready for the upgrade. This will reads data from the database and does not perform any updates.

Execute AutoUpgrade in analyze mode with the below syntax:

export ORACLE HOME=/u01/app/oracle/product/19.0.0/db_1
export PATH=$PATH:$ORACLE_HOME/jdk/bin

cd /home/oracle/auto_upgrade_19c

$ORACLE_HOME/jdk/bin/java -jar $ORACLE_HOME/rdbms/admin/autoupgrade.jar -config prddb_config.cfg -mode ANALYZE

We can monitor, manage and control the jobs from the autoupgrade console.

  • lsj – to list the jobs
  • status – to show the job status
  • tasks – shows the tasks executing

Crosscheck and verify all logs before proceeding further

Deploy the upgrade and monitor

  • Auto upgrade Deploy mode performs the actual upgrade of the database from pre-upgrade source database analysis to post-upgrade checks.
  • Before starting Deploy make sure you have taken a backup of your database.

$ORACLE_HOME/jdk/bin/java -jar $ORACLE_HOME/rdbms/admin/autoupgrade.jar -config
prod_db_config.cfg -mode DEPLOY

  • Once the upgrade process is started consider monitoring the logs and database alert logs to see the progress of the upgrade. Auto upgrade logs are available under

/home/oracle/auto_upgrade_19c/upg_logs/

Once the upgrade finishes crosscheck the below.

SELECT VERSION FROM V$TIMEZONE_FILE;
select name, open_mode, version, status from v$database, v$instance;

Post-upgrade task

  • Once the upgrade is successful and all testing is done, drop the restore point.
  • Drop the Guaranteed restore point

select name from v$restore_point;
drop restore point restorepoint_name;

  • Change the compatible parameter
  • After the upgrade, the database has to be tested properly before updating the compatible parameter. Once the parameter is updated database cannot be downgraded.

show parameter compatible;
alter system set compatible=’19.0.0′ scope=spfile;
shutdown immediate:
startup;
show parameter compatible;

Hope this blog was useful…

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How to find the bind variable values of the SQL statement using SQLID?

How to find the bind variable values of the SQL statement using SQLID?

SELECT sql_id,  b.name BIND_NAME,  b.value_string BIND_STRING   from gv$sql t
JOIN gv$sql_bind_capture b USING (sql_id) WHERE b.value_string IS NOT NULL
AND sql_id ='&SQLID';

Additional script which may be helpful at a later point in time:

To know the last executed query in the oracle and its hash value,sqlid

SELECT * FROM v$SQLTEXT_WITH_NEWLINES WHERE address =
  (SELECT prev_sql_addr FROM v$session WHERE audsid = userenv('SESSIONID'))
ORDER BY piece;

To know the SQL plan history of a sql using the sqlid:

select * from TABLE(DBMS_XPLAN.DISPLAY_AWR('&sqlid'));

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ARCHIVELOG MODE

How to Enable archive log mode

Once you have configured the flash recovery area, you can put the database in ARCHIVELOG mode. Unfortunately, this requires that the database be shutdown first with the shutdown command (however, from earlier in the chapter, we note that shutdown immediate is the best option). Once you have shutdown the database, you will start the database in mount Stage with the startup mount command. Then put the database in ARCHIVELOG mode, and finally open the database. Here is an example of how this all works from the command line.

SQL> archive log list;


Database log mode               No Archive Mode
Automatic archival              Disabled
Archive destination             d:oracleoradataDB10Garchive
Oldest online log sequence      427
Current log sequence            429

SQL> shutdown immediate;

Database closed.
Database dismounted.
ORACLE instance shut down.

SQL> startup mount
ORACLE instance started.

Total System Global Area 1610609200 bytes
Fixed Size               8897072 bytes
Variable Size            385875968 bytes
Database Buffers         1207959552 bytes
Redo Buffers             7876608 bytes
Database mounted.

SQL> alter database archivelog;

Database altered.

SQL> alter database open;

Database altered.

SQL> archive log list;

Database log mode                  Archive Mode
Automatic archival                 Enabled
Archive destination                d:oracleoradataDB10Garchive
Oldest online log sequence         426
Next log sequence to archive       427
Current log sequence               428

How to Disable archive log mode

SQL> archive log list;

Database log mode                Archive Mode
Automatic archival               Enabled
Archive destination              d:oracleoradataDB10Garchive
Oldest online log sequence       426
Next log sequence to archive     427
Current log sequence             428


SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.

SQL> startup mount
ORACLE instance started.

Total System Global Area 1610609200 bytes
Fixed Size               8897072 bytes
Variable Size            385875968 bytes
Database Buffers         1207959552 bytes
Redo Buffers             7876608 bytes
Database mounted.


SQL> alter database noarchivelog;

Database altered.

SQL> alter database open;

Database altered.


SQL> archive log list;

Database log mode                NoArchive Mode
Automatic archival               Enabled
Archive destination              d:oracleoradataDB10Garchive
Oldest online log sequence       426
Next log sequence to archive     427
Current log sequence             428

Change Archive log mode and Destination in oracle 19c

[oracle@training ~]$ export ORACLE_SID=training1

[oracle@training ~]$ sqlplus / as sysdba

SQL*Plus: Release 19.0.0.0.0 - Production on Wed Jul 28 23:30:16 2021
Version 19.3.0.0.0

Copyright (c) 1982, 2019, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> startup

ORACLE instance started.

Total System Global Area 2432695144 bytes
Fixed Size                  8899432 bytes
Variable Size             536870912 bytes
Database Buffers         1879048192 bytes
Redo Buffers                7876608 bytes
Database mounted.
Database opened.
SQL> archive log list;
Database log mode              No Archive Mode
Automatic archival             Disabled
Archive destination            USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence     89
Current log sequence           91

SQL> exit
Disconnected from Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - 
Production Version 19.3.0.0.0 [oracle@training ~]$ mkdir -p /u01/ARC_BKP [oracle@training ~]$ sqlplus / as sysdba SQL*Plus: Release 19.0.0.0.0 - Production on Wed Jul 28 23:38:09 2021 Version 19.3.0.0.0 Copyright (c) 1982, 2019, Oracle. All rights reserved. Connected to: Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production Version 19.3.0.0.0

To check the current archiving location

SQL> SHOW PARAMETER DB_RECOVERY_FILE_DEST

NAME                       TYPE            VALUE
---------------------  ---------------   --------------
db_recovery_file_dest       string      /u01/app/oracle /fast_recovery_area
                                                 
db_recovery_file_dest_size  big integer  8256M
SQL> alter system set DB_RECOVERY_FILE_DEST='/u01/ARC_BKP';

System altered.

SQL> alter system set log_archive_dest=’/u01/ARC_BKP’;

System altered.

SQL> alter database close;

Database altered.

SQL> alter database archivelog;

Database altered.

SQL> shut immediate
ORA-01109: database not open
Database dismounted.
ORACLE instance shut down.

SQL> exit
Disconnected from Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 -
Production Version 19.3.0.0.0 [oracle@training u01]$ sqlplus / as sysdba SQL*Plus: Release 19.0.0.0.0 - Production on Wed Jul 28 23:52:05 2021 Version 19.3.0.0.0 Copyright (c) 1982, 2019, Oracle. All rights reserved. Connected to an idle instance. SQL> startup ORACLE instance started. Total System Global Area 2432695144 bytes Fixed Size 8899432 bytes Variable Size 536870912 bytes Database Buffers 1879048192 bytes Redo Buffers 7876608 bytes Database mounted. Database opened. SQL> archive log list; Database log mode Archive Mode Automatic archival Enabled Archive destination /u01/ARC_BKP Oldest online log sequence 89 Next log sequence to archive 91 Current log sequence 91

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Control file Multiplexing

Static and Dynamic

MULTIPLEXING USING SPFILE

SQL> select name from v$controlfile;

NAME
------------------------------------------------------------------
/u01/app/oracle/oradata/TRAINING/controlfile/o1_mf_j9bdm6dk_.ctl
/u01/app/oracle/oradata/TRAINING/controlfile/o1_mf_j9bdm6dk_1.ctl
SQL> alter system set control_files=
'/u01/app/oracle/oradata/TRAINING/controlfile/o1_mf_j9bdm6dk_.ctl',
'/u01/app/oracle/oradata/TRAINING/controlfile/o1_mf_j9bdm6dk_1.ctl',
'/u01/app/oracle/oradata/TRAINING/control01.dbf' scope=spfile; System altered.
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.


SQL> !cp /u01/app/oracle/oradata/TRAINING/controlfile/o1_mf_j9bdm6dk_.ctl 
/u01/app/oracle/oradata/TRAINING/control01.dbf
SQL> startup

ORACLE instance started.

Total System Global Area 2432695144 bytes
Fixed Size                  8899432 bytes
Variable Size             536870912 bytes
Database Buffers         1879048192 bytes
Redo Buffers                7876608 bytes

Database mounted.

Database opened.
SQL> select name from v$controlfile;

NAME
--------------------------------------------------------------------------------
/u01/app/oracle/oradata/TRAINING/controlfile/o1_mf_j9bdm6dk_.ctl
/u01/app/oracle/oradata/TRAINING/controlfile/o1_mf_j9bdm6dk_1.ctl
/u01/app/oracle/oradata/TRAINING/control01.dbf

SQL> create pfile from spfile;

File created.

MULTIPLEXING USING PFILE

Multiplexing is the process of mintaining a copy of same control files on different disk drivers (and idealy on different controllers). To multiplex your control files, we copy the control file to multiple locations and change the CONTROL_FILES parameter in the text based initialization file init.ora to include all control files names.

SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.

SQL> exit
Disconnected from Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - 
Production Version 19.3.0.0.0
[oracle@training ~]$ cd $ORACLE_HOME/dbs


[oracle@training dbs]$ vi inittraining.ora


*.control_files='/u01/app/oracle/oradata/TRAINING/controlfile/o1_mf_j9bdm6dk_.ctl',
'/u01/app/oracle/oradata/TRAINING/controlfile/o1_mf_j9bdm6dk_1.ctl',
'/u01/app/oracle/oradata/TRAINING/control01.dbf'
[oracle@training dbs]$ cp /u01/app/oracle/oradata/TRAINING/control01.dbf 
/u01/app/oracle/oradata/TRAINING/control02.dbf [oracle@training dbs]$ sqlplus / as sysdba SQL> startup pfile=$ORACLE_HOME/dbs/inittraining1.ora ORACLE instance started. Total System Global Area 2432695144 bytes Fixed Size 8899432 bytes Variable Size 536870912 bytes Database Buffers 1879048192 bytes Redo Buffers 7876608 bytes Database mounted. Database opened.
SQL> select name from v$controlfile;

NAME
--------------------------------------------------------------------------------
/u01/app/oracle/oradata/TRAINING1/controlfile/o1_mf_j9bdm6dk_.ctl
/u01/app/oracle/oradata/TRAINING1/controlfile/o1_mf_j9bdm6dk_1.ctl
/u01/app/oracle/oradata/TRAINING1/control01.dbf
/u01/app/oracle/oradata/TRAINING1/control02.dbf


SQL> create spfile from pfile;

File created.

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NID Utility in Oracle

DBNEWID is a database utility, in $ORACLE_HOME/bin directory, that can change the internal database identifier (DBID) and the database name (DBNAME) for an operational database. Prior to the introduction of the DBNEWID utility, we used to manually create a copy of a database and give it a new database name (DBNAME) by re-creating the control file. However, alteration of the internal database identifier (DBID) of an instance was impossible.

The DBID is an internal, unique identifier for a database. Because Recovery Manager(RMAN)  distinguishes databases by DBID, you could not register a seed database and a manually copied database together in the same RMAN repository. The DBNEWID utility solves this problem.

NID utility allows us to change

  • Only DBID of a database
  • Only DBNAME of a database
  • Both DBNAME and DBID of a database

Changing the DBID of a database is a serious procedure. When the DBID of a database is changed all previous backups and archived logs of the database become unusable. After you change the DBID, you must open the database with the RESETLOGS option, which re-creates the online redo logs and resets their sequence to 1. Consequently, you should make a backup of the whole database immediately after changing the DBID.

Changing DBNAME & DBID

SQL> select dbid, name from v$database;

   DBID          NAME
----------    ---------
 247698686    TRAINING

SQL> SHUTDOWN IMMEDIATE
Database closed.
Database dismounted.
ORACLE instance shut down.

SQL>  STARTUP MOUNT
ORACLE instance started.

Total System Global Area 2432695144 bytes
Fixed Size                  8899432 bytes
Variable Size             536870912 bytes
Database Buffers         1879048192 bytes
Redo Buffers                7876608 bytes
Database mounted.

SQL> exit
Disconnected from Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - 
Production Version 19.3.0.0.0 [oracle@training ~]$ nid TARGET=sqlplus / as sysdba DBNAME=testdb LOGFILE=testdb.log Password:
SQL> select status from v$instance;

STATUS
------------
STARTED

SQL> alter database mount;
alter database mount
*
ERROR at line 1:
ORA-01103: database name 'TESTDB' in control file is not 'TRAINING'

[oracle@training ~]$ cd $ORACLE_HOME/dbs
[oracle@training ~]$ vi inittraining1.ora

training1.__data_transfer_cache_size=0
training1.__db_cache_size=1728053248
training1.__inmemory_ext_roarea=0
training1.__inmemory_ext_rwarea=0
training1.__java_pool_size=0
training1.__large_pool_size=16777216
training1.__oracle_base='/u01/app/oracle'#ORACLE_BASE set from environment
training1.__pga_aggregate_target=822083584
training1.__sga_target=2432696320
training1.__shared_io_pool_size=117440512
training1.__shared_pool_size=520093696
training1.__streams_pool_size=0
training1.__unified_pga_pool_size=0
*.audit_file_dest='/u01/app/oracle/admin/training1/adump'
*.audit_trail='db'
*.compatible='19.0.0'
*.control_files='/u01/app/oracle/oradata/TRAINING1/control01,dbf','
/u01/app/oracle/oradata/TRAINING1/control02.dbf'
*.db_16k_cache_size=33554432
*.db_block_size=8192
*.db_create_file_dest='/u01/app/oracle/oradata'
*.db_name='testdb'
*.db_recovery_file_dest_size=8256m
*.db_recovery_file_dest='/u01/ARC_BKP'
*.db_unique_name='training1'
*.deferred_segment_creation=FALSE
*.diagnostic_dest='/u01/app/oracle'
*.dispatchers='(PROTOCOL=TCP) (SERVICE=training1XDB)'
*.open_cursors=300
*.pga_aggregate_target=771m
*.processes=300
*.remote_login_passwordfile='EXCLUSIVE'
*.sga_target=2312m
*.undo_tablespace='UNDOTBS1'
[oracle@training dbs]$ . oraenv
ORACLE_SID = [training] ?
The Oracle base remains unchanged with value /u01/app/oracle
[oracle@training dbs]$ sqlplus / as sysdba

SQL*Plus: Release 19.0.0.0.0 - Production on Thu Jul 29 02:57:59 2021
Version 19.3.0.0.0

Copyright (c) 1982, 2019, Oracle.  All rights reserved.

Connected to an idle instance.
SQL> startup pfile=$ORACLE_HOME/dbs/inittraining.ora
ORACLE instance started.

Total System Global Area 2432695144 bytes
Fixed Size                  8899432 bytes
Variable Size             536870912 bytes
Database Buffers         1879048192 bytes
Redo Buffers                7876608 bytes
Database mounted.
ORA-01589: must use RESETLOGS or NORESETLOGS option for database open


SQL> alter database open resetlogs;

Database altered.
 ‌
SQL> select dbid,name from v$database;
 
      DBID         NAME
----------       ---------
2862448691        TESTDB

SQL> select status,instance_name from v$instance;

STATUS       INSTANCE_NAME
------------ ----------------
OPEN            training


SQL> create spfile from pfile;

File created.

SQL> show parameter spfile;

NAME             TYPE        VALUE
------------- ----------- ------------------------------
spfile         string      /u01/app/oracle/product/19.0.0
                           /dbhome_1/dbs/spfiletraining.ora
                                                 

Change the only DBNAME

SQL> shut immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.

SQL> startup mount
ORACLE instance started.

Total System Global Area 2432695144 bytes
Fixed Size                  8899432 bytes
Variable Size             536870912 bytes
Database Buffers         1879048192 bytes
Redo Buffers                7876608 bytes
Database mounted.
SQL> exit
Disconnected from Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - 
Production Version 19.3.0.0.0 [oracle@training ~]$ nid target=sqlplus / as sysdba dbname=training setname=yes DBNEWID: Release 19.0.0.0.0 - Production on Thu Jul 29 21:48:14 2021 Copyright (c) 1982, 2019, Oracle and/or its affiliates. All rights reserved. Password: Connected to database TESTDB (DBID=2862448691) Connected to server version 19.3.0 Control Files in database: /u01/app/oracle/oradata/TRAINING1/control01.dbf /u01/app/oracle/oradata/TRAINING1/control02.dbf Change database name of database TESTDB to TRAINING? (Y/[N]) => y Proceeding with operation Changing database name from TESTDB to TRAINING Control File /u01/app/oracle/oradata/TRAINING1/control01.dbf -modified Control File/u01/app/oracle/oradata/TRAINING1/control02.dbf - modified Datafile /u01/app/oracle/oradata/TRAINING1/system.dbf - wrote new name Datafile /u01/app/oracle/oradata/TRAINING1/sysaux.dbf - wrote new name Datafile /u01/app/oracle/oradata/TRAINING1/undo.dbf - wrote new name Datafile /u01/app/oracle/oradata/TRAINING1/users.dbf - wrote new name Datafile /u01/app/oracle/oradata/TRAINING1/temp.tmp - wrote new name Instance shut down Database name changed to TRAINING. Modify parameter file and generate a new password file before restarting. Succesfully changed database name. DBNEWID - Completed succesfully.
[oracle@training ~]$ cd $ORACLE_HOME/dbs

[oracle@training dbs]$ vi inittraining1.ora

training1.__data_transfer_cache_size=0
training1.__db_cache_size=1728053248
training1.__inmemory_ext_roarea=0
training1.__inmemory_ext_rwarea=0
training1.__java_pool_size=0
training1.__large_pool_size=16777216
training1.__oracle_base='/u01/app/oracle'#ORACLE_BASE set from environment
training1.__pga_aggregate_target=822083584
training1.__sga_target=2432696320
training1.__shared_io_pool_size=117440512
training1.__shared_pool_size=520093696
training1.__streams_pool_size=0
training1.__unified_pga_pool_size=0
*.audit_file_dest='/u01/app/oracle/admin/training1/adump'
*.audit_trail='db'
*.compatible='19.0.0'
*.control_files='/u01/app/oracle/oradata/TRAINING1/control01,dbf','
/u01/app/oracle/oradata/TRAINING1/control02.dbf'
*.db_16k_cache_size=33554432
*.db_block_size=8192
*.db_create_file_dest='/u01/app/oracle/oradata'
*.db_name='training'
*.db_recovery_file_dest_size=8256m
*.db_recovery_file_dest='/u01/ARC_BKP'
*.db_unique_name='training1'
*.deferred_segment_creation=FALSE
*.diagnostic_dest='/u01/app/oracle'
*.dispatchers='(PROTOCOL=TCP) (SERVICE=training1XDB)'
*.open_cursors=300
*.pga_aggregate_target=771m
*.processes=300
*.remote_login_passwordfile='EXCLUSIVE'
*.sga_target=2312m
*.undo_tablespace='UNDOTBS1'

[oracle@training dbs]$ . oraenv
ORACLE_SID = [training1] ?
The Oracle base remains unchanged with value /u01/app/oracle
[oracle@training dbs]$ sqlplus / as sysdba

SQL*Plus: Release 19.0.0.0.0 - Production on Thu Jul 29 21:52:50 2021
Version 19.3.0.0.0

Copyright (c) 1982, 2019, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> startup pfile='$ORACLE_HOME/dbs/inittraining1.ora'
ORACLE instance started.

Total System Global Area 2432695144 bytes
Fixed Size               8899432 bytes
Variable Size            536870912 bytes
Database Buffers         1879048192 bytes
Redo Buffers             7876608 bytes
Database mounted.
Database opened.

SQL> select name from v$database;

NAME
---------
TRAINING

SQL> select status,instance_name from v$instance;

STATUS       INSTANCE_NAME
--------- ----------------
OPEN         training1

Change only DBID

SQL> shut immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.

SQL> startup mount
ORACLE instance started.

Total System Global Area 2432695144 bytes
Fixed Size                  8899432 bytes
Variable Size             536870912 bytes
Database Buffers         1879048192 bytes
Redo Buffers                7876608 bytes
Database mounted.
SQL> exit
Disconnected from Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - 
Production Version 19.3.0.0.0 [oracle@training dbs]$ nid target=sqlplus / as sysdba DBNEWID: Release 19.0.0.0.0 - Production on Thu Jul 29 22:58:56 2021 Copyright (c) 1982, 2019, Oracle and/or its affiliates. All rights reserved. Password: Connected to database TRAINING (DBID=2862448691) Connected to server version 19.3.0 Control Files in database: /u01/app/oracle/oradata/TRAINING1/control01.dbf /u01/app/oracle/oradata/TRAINING1/control02.dbf Change database ID of database TRAINING? (Y/[N]) => y Proceeding with operation Changing database ID from 2862448691 to 254963316 Control File /u01/app/oracle/oradata/TRAINING1/control01.dbf - modified Control File /u01/app/oracle/oradata/TRAINING1/control02.dbf - modified Datafile /u01/app/oracle/oradata/TRAINING1/system.dbf - dbid changed Datafile /u01/app/oracle/oradata/TRAINING1/sysaux..dbf - dbid changed Datafile /u01/app/oracle/oradata/TRAINING1/undo.dbf - dbid changed Datafile /u01/app/oracle/oradata/TRAINING1/users.dbf - dbid changed Datafile /u01/app/oracle/oradata/TRAINING1/data01.dbf - dbid changed Datafile /u01/app/oracle/oradata/TRAINING1/temp.tmp - dbid changed Control File /u01/app/oracle/oradata/TRAINING1/control01.dbf - dbid changed Control File /u01/app/oracle/oradata/TRAINING1/control02.dbf - dbid changed Instance shut down Database ID for database TRAINING changed to 254963316. All previous backups and archived redo logs for this database are unusable. Database is not aware of previous backups and archived logs in Recovery Area. Database has been shutdown, open database with RESETLOGS option. Succesfully changed database ID. DBNEWID - Completed successfully.
[oracle@training dbs]$ sqlplus / as sysdba

SQL*Plus: Release 19.0.0.0.0 - Production on Thu Jul 29 22:59:46 2021
Version 19.3.0.0.0

Copyright (c) 1982, 2019, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> startup mount;
ORACLE instance started.

Total System Global Area 2432695144 bytes
Fixed Size                  8899432 bytes
Variable Size             536870912 bytes
Database Buffers         1879048192 bytes
Redo Buffers                7876608 bytes
Database mounted.

SQL> alter database open resetlogs;

Database altered.

SQL> select name,dbid from v$database;

NAME            DBID
---------   ----------
TRAINING     254963316

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LMT AND DMT TABLESPACE

LMT TABLESPACE

The LMT tablespace is implemented by adding EXTENT MANAGEMENT LOCAL clause to 
the tablespace definition.LMT tablespaces automate extent management and remove
the ability to specify the NEXT storage parameter.

The only exception is when NEXT is used with MINEXTENTS at table creation time. LMT means Locally Management system,LMT tablespace size is uniform. By default uniform size is 1,By default lmt tablespace is Autoallocate.

Auto allocate

SQL> create tablespace india datafile '/u01/app/oracle/oradata/TESTDB/india01.dbf' 
size 50m; Tablespace created.

Uniform Size

SQL> create tablespace USA datafile '/u01/app/oracle/oradata/TESTDB/USA01.dbf' 
size 50m extent management local uniform size 512k; Tablespace created.

Deferred segment creation

SQL> create table india (reg_id number,reg_name varchar2(200));

Table created.

SQL>  select count(*) from dba_segments where segment_name='INDIA';

  COUNT(*)
----------
        0
SQL> select count(*) from dba_extents where segment_name='INDIA';

  COUNT(*)
----------
         0
SQL> insert into india values (5,'tamil');

1 row created.

SQL>  select count(*) from dba_segments where segment_name='INDIA';

  COUNT(*)
----------
         1

SQL>  select count(*) from dba_extents where segment_name='INDIA';

  COUNT(*)
----------
         1
SQL>  create table italy (reg_no number,reg_name varchar2(2000)) 
segment creation immediate;

Table created.


SQL> show parameter deferred_segment_creation;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
deferred_segment_creation            boolean     TRUE

SQL> alter system set deferred_segment_creation=false;

System altered.

SQL>  show parameter deferred_segment_creation;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
deferred_segment_creation            boolean     FALSE

Extents

Continuous blocks it’s called extents,Data Stored in blocks,blocks Stored in extents.
By default Extents Size 64k.

TYPES OF EXTENTS

Initial          - Initial is First No of transaction by default 100.

Next             - Next no of transaction is 200.
  
Minextents       - minimum number of transactions by default 1.

Maxextents       - maximum number of transactions by default Unlimited.

Pct increase     - pct increase by default 100.

BLOCKS

Smallest storage unit it’s called Blocks.After database creation 
we can specify block size but before database creation we can’t change block size.
block size is 2k,4k,8k,16k,32k. By default Block size is 8k.

Check Block Size in Database

SQL> show parameter db_block_size;

NAME                     TYPE        VALUE
--------------------- ----------- --------------
db_block_size           integer     8192

SQL> select block_size,tablespace_name from dba_tablespaces;

BLOCK_SIZE            TABLESPACE_NAME
----------        ------------------------------
      8192 	        SYSTEM
      8192 		SYSAUX
      8192 		UNDOTBS1
      8192 		TEMP
      8192 		USERS
      8192 		TEST
      8192 		INDIA

create New Tablespace

SQL>  create tablespace spain datafile'/u01/app/oracle/oradata/TESTDB/spain01,dbf'
size 100m blocksize 16k; Tablespace created.
SQL>  select block_size,tablespace_name from dba_tablespaces;

BLOCK_SIZE        TABLESPACE_NAME
----------      ---------------------
      8192            SYSTEM
      8192            SYSAUX
      8192            UNDOTBS1
      8192  	      TEMP
      8192 	      USERS
      8192 	      TEST
      8192 	      INDIA
     16384 	      SPAIN

Block Utilization Parameters

INITRANS       

MAXTRANS    

PCTUSED        

PCTFREE   
Initans is the initial number of transactions by default 1. 
Maxtrans is Maximum number of Transactions default 255.Inserted data Stored in
pct used by default allocate space is 89%, in case pct used is full Remaining
data goes to Next pct used. Update happens in pct free by default allocate space 10%,
pct used and pct free information stored by block header by default allocated space 1%.

Block-level problems

Row chaining

Row migration

Row chaining

Inserted data stored in pct used,that pct used is full remaining data goes to next pct 
used it is called Row chaining.Row chaining occurs when a row can't physically fit
into an Oracle block.

Another block is required to store the remainder of the row.Chaining can cause serious
performance problems and is especially prevalent with those storing multimedia data or
large binary objects (blobs).

You should pay special attention to the DB_BLOCK_SIZE parameter
when you create your database.Block sizes of 4 kilobytes or more are the norm,
not the exception.

Row migration

Date updates happen for  pct free ,that updated data stored in pct used.pct used is 
full that time remaining data goes to the next pct used that is called row Migration. Migration of an Oracle row occurs when a row is updated in an Oracle block and the
amount of free space in the block is not adequate to store all of the row's data.
The row is migrated to another physical block in the table.
The problem is that the indexes that refer to the migrated row are still pointing
to the block where the row used to be, and hence the table reads are doubled.
Note however that full table scans will scan blocks as they come and will perform the
same number of reads whether the rows are migrated or not.

 

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Check unusable and invalid index in Oracle

 

Check unusable and not valid Index in Oracle

Below Query will convert all the unusable and not valid indexes in Oracle. The query will cover the complete index with partition index and subpartition index.

The result will give you the rebuild command of the invalid or unusable indexes.
You can directly run that and on sqlplus and make them a valid or usable state.

QUERY :

SELECT 'ALTER INDEX ' || OWNER || '.' ||
INDEX_NAME || ' REBUILD ' ||
' TABLESPACE ' || TABLESPACE_NAME || ';'
FROM DBA_INDEXES
WHERE STATUS='UNUSABLE'
UNION
SELECT 'ALTER INDEX ' || INDEX_OWNER || '.' ||
INDEX_NAME ||
' REBUILD PARTITION ' || PARTITION_NAME ||
' TABLESPACE ' || TABLESPACE_NAME || ';'
FROM DBA_IND_PARTITIONS
WHERE STATUS='UNUSABLE'
UNION
SELECT 'ALTER INDEX ' || INDEX_OWNER || '.' ||
INDEX_NAME ||
' REBUILD SUBPARTITION '||SUBPARTITION_NAME||
' TABLESPACE ' || TABLESPACE_NAME || ';'
FROM DBA_IND_SUBPARTITIONS
WHERE STATUS='UNUSABLE';

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FLASHBACK VERSION QUERY

FLASHBACK VERSION QUERY

Flashback version query allows the versions of a specific row to be tracked during a specified time period using the VERSIONS BETWEEN clause.

Flashback version query is based on UNDO. As a result, the amount of time you can flashback is dependent on how long undo information is retained, as specified by the UNDO_RETENTION parameter.

SQL> CREATE TABLE flashback_version_query_test (id NUMBER(10),description  VARCHAR2(50));

Table created.

SQL> INSERT INTO flashback_version_query_test (id, description) VALUES (1, 'ONE');

1 row created.

SQL> commit;

Commit complete.

SQL> SELECT current_scn, TO_CHAR(SYSTIMESTAMP, 'YYYY-MM-DD HH24:MI:SS') FROM v$database;

CURRENT_SCN    TO_CHAR(SYSTIMESTAM
-----------   -------------------
    4991867    2021-07-20 22:29:52

SQL> UPDATE flashback_version_query_test SET description = 'TWO' WHERE id = 1;

1 row updated.

SQL> commit;

Commit complete.


SQL> UPDATE flashback_version_query_test SET description = 'THREE' WHERE id = 1;

1 row updated.

SQL> commit;

Commit complete.

SQL> SELECT current_scn, TO_CHAR(SYSTIMESTAMP, 'YYYY-MM-DD HH24:MI:SS') FROM v$database;

CURRENT_SCN  TO_CHAR(SYSTIMESTAM
-----------  -------------------
    4992195  2021-07-20 22:34:30


SQL>  SELECT versions_startscn, versions_starttime,versions_endscn, versions_endtime, 
versions_xid, versions_operation, description from flashback_version_query_test
VERSIONS BETWEEN TIMESTAMP TO_TIMESTAMP(' 2021-07-20 22:29:52', 'YYYY-MM-DD HH24:MI:SS')
AND TO_TIMESTAMP('2021-07-20 22:34:30', 'YYYY-MM-DD HH24:MI:SS')WHERE id = 1; VERSIONS_STARTSCN VERSIONS_STARTTIME VERSIONS_ENDSCN VERSIONS_ENDTIME VERSIONS_XID V DESCRIPTION ---------- --------------------- ------------------ -------------- ----------- ----------- 4992172 20-JUL-21 10.33.41 PM 0D0020001B040000 U THREE 4992136 20-JUL-21 10.32.23 PM 0B00050021040000 U TWO 4992172 20-JUL-21 10.33.41 PM ON
E SQL> SELECT versions_startscn, versions_starttime, versions_endscn, versions_endtime,
versions_xid, versions_operation, description FROM flashback_version_query_test VERSIONS BETWEEN SCN 4991867 and 4992195 WHERE id = 1; VERSIONS_STARTSCN VERSIONS_STARTTIME VERSIONS_ENDSCN VERSIONS_ENDTIME VERSIONS_XID V DESCRIPTION ------------------ ------------------------ ------------------ ------------------------ ---------------- - ----------- 4992172 20-JUL-21 10.33.41 PM 0D0020001B040000 U THREE 4992136 20-JUL-21 10.32.23 PM 4992172 20-JUL-21 10.33.41 PM 0B00050021040000 U TWO 4992136 20-JUL-21 10.32.23 PM ONE SQL> SELECT xid, operation, start_scn,commit_scn, logon_user, undo_sql FROM
flashback_transaction_query WHERE xid = HEXTORAW('06000000FA030000');

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FLASHBACK DROP TABLE (RECYCLE BIN)

FLASHBACK DROP TABLE

The recycle bin is a logical collection of previously dropped objects. This feature doesn’t use flashback logs or undo, so it is distinct from the other flashback technologies.

Enable/Disable Recycle Bin

SQL> show parameter recyclebin;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
recyclebin                           string      OFF

SQL> alter session set recyclebin = on;

Session altered.

SQL> show parameter recyclebin;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
recyclebin                           string      ON

 (RECYCLE BIN)

SQL> CREATE TABLE flashback_drop_test (id  NUMBER(10));

Table created.

SQL> INSERT INTO flashback_drop_test (id) VALUES (1);

1 row created.

SQL> commit;

Commit complete.


SQL> DROP TABLE flashback_drop_test;

Table dropped.

SQL> show recyclebin;

ORIGINAL NAME    RECYCLEBIN NAME                OBJECT TYPE  DROP TIME
---------------- ------------------------------ ------------ -------------------
FLASHBACK_DROP_T BIN$TstgCMiwQA66fl5FFDTBgA==$0 TABLE        2004-03-29:11:09:07
EST

SQL> FLASHBACK TABLE flashback_drop_test TO BEFORE DROP;

SELECT * FROM flashback_drop_test;

        ID
----------
         1
Rename Table

SQL> show RECYCLEBIN;

ORIGINAL NAME	 RECYCLEBIN NAME		OBJECT TYPE  DROP TIME
---------------- ------------------------------ ------------ -------------------
S		 BIN$x3mKgoseD/7gUxkBqMAnAA==$0 TABLE	     2021-07-19:17:20:17
SQL> create table s(n number);

Table created.

SQL> FLASHBACK TABLE s TO BEFORE DROP;
FLASHBACK TABLE s TO BEFORE DROP
*
ERROR at line 1:
ORA-38312: original name is used by an existing object


SQL> FLASHBACK TABLE s TO BEFORE DROP rename to b;

Flashback complete.

SQL> select * from b;

no rows selected

SQL> show RECYCLEBIN;

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