How to deinstall Oracle 11g database software

In oracle 11g, you can use the deinstall script supplied in the $ORACLE_HOME/deinstall folder, as shown below.

In my example, I have two Oracle software installations on the host

/u01/oracle/product/11203 <-- not in use, can be removed

/u01/oracle/product/11204 <-- in use

cd /tmp

# first perform a trial run

/u01/oracle/product/11203/deinstall/deinstall -checkonly

# do the actual deinstall

/u01/oracle/product/11203/deinstall/deinstall

I have found that when you have a listener running on the host out of a different ORACLE_HOME, the deinstall script will often (but not always) want to deconfigure it, despite the fact that it runs out of a different ORACLE_HOME. So for a brief period, the host may be without a valid listener process. However, this was never a problem , simply change directory to the working /u01/oracle/product/11204/network/admin folder and restart the listener.

Sometimes (but not always) you may have to manually remove the deinstall folder under the ORACLE_HOME home you just deinstalled.

How to add a logfile group and a logfile member - syntax

alter database add logfile group 2
(
'/u01/app/oracle/flash_recovery_area/mydb/onlinelog/redo02a.log',
'/u01/app/oracle/oradata/mydb/onlinelog/redo02b.log'
) size 50M;

Remember, if you have just recently dropped the redo log members, they are still present physically on disk.
If you'd like to reuse the log file member names, and to avoid

ORA-00301: error in adding log file /u03/oradata/arutvt/redo03.log - file cannot be created,

add the REUSE keyword at the end of the statement:

alter database add logfile group 3 ('/u03/oradata/mydb/redo03.log') size 1024M REUSE;

To add another member to an already existing group:

ALTER DATABASE ADD LOGFILE MEMBER '/u03/oradata/mydb/redo03.log' TO GROUP 3;

If the redo log file member is already present on disk, use reuse:

ALTER DATABASE ADD LOGFILE MEMBER '/u03/oradata/mydb/redo3b.log' REUSE TO GROUP 3;

If you do not specifically say which log group number you want to create, Oracle will take add another group based on the largest log file group number in v$logfile. So if I have 3 groups already, and execute

alter database add logfile '/rdodata/mydb/redo04.log' size 2048M;

It will create group number 4 for you, even if you do not explicitly say so:

SYS@cdb>SQL>@redo

    GROUP# MEMBER                                                     MB ARC STATUS            SEQUENCE#
---------- -------------------------------------------------- ---------- --- ---------------- ----------
         1 /rdodata/mydbredo01.log                              2048 YES INACTIVE                220
         2 /rdodata/mydb/redo02.log                             2048 YES INACTIVE                221
         3 /rdodata/mydb/redo03.log                             2048 NO  CURRENT                 222
         4 /rdodata/mydb/redo04.log                             2048 YES UNUSED                    0

Documentation for Oracle 19c is found here

How to find information about CPUs on a Linux server

On RHEL-based Linux distributions, cat the file /proc/cpuinfo, and you will find detailed information about the server's CPUs, including model name, cache size and vendor.

cat /proc/cpuinfo | grep processor
processor       : 0
processor       : 1
processor       : 2
processor       : 3

Or

 lscpu
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                4
On-line CPU(s) list:   0-3
Thread(s) per core:    1
Core(s) per socket:    1
Socket(s):             4
NUMA node(s):          1
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 58
Stepping:              0
CPU MHz:               2800.000
BogoMIPS:              5600.00
Hypervisor vendor:     VMware
Virtualization type:   full
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              25600K
NUMA node0 CPU(s):     0-3

How to execute a stored dbms_scheduler job

In sqlplus, execute the following:

execute dbms_scheduler.run_job('CHANGE_PERMS',TRUE);

How to select rows from a specific partition

The syntax to use if you want to select directly from a specific partition:

SELECT row1, row2 ... 
FROM       my_partitioned_table
PARTITION (my_partition_name)
WHERE ....;

From a subpartition:

SELECT row1, row2 ... 
FROM       my_partitioned_table
SUBPARTITION (my_subpartition_name)
WHERE ....;

With Oracle 11g interval partitioning, the syntax has changed so that you can reference a date range, rather than a partition name, since the auto generated names won't say anything meaningful about their content:

select row1, row2 ..
from my_partitioned_table
PARTITION FOR (to_date('25-FEB-2015','dd-mon-yyyy')); 

Remember that aliases must be specified after the entire FROM-clause, including the PARTITION-part, like this:

select ee.col1
from my_partitioned_table
partition (SYS_P2447) ee
where ee.col2 = 'string1'
and ee.col3 like '%string2%'
order by ee.col1,col2;

If you place the alias immediately after the table name, you'll get the error:

partition (SYS_P2447)
          *
ERROR at line 3:
ORA-00924: missing BY keyword

upon execution.

What do do when Oracle Universal Installer reports missing package pdksh-5.2.14 oracle

On RHEL 6, if you encounter situations where the OUI is complaining about the absence of a package pdksh-5.2.14 oracle, do the following:

1. Change directory to /database/stage/cvu/cv/admin 

2. Backup cvu_config: % cp cvu_config backup_cvu_config

3. Edit cvu_config and change the following line:

CV_ASSUME_DISTID=OEL4

to:

CV_ASSUME_DISTID=OEL6

4. Save the updated cvu_config file
5. Install the 11.2.0.3 or 11.2.0.4 software using /database/runInstaller

% cd /database
% ./runInstaller

When installing a 32-bit client like in my case, the OUI will warn that "all requirements have not been met".
This message can be ignored and you can proceed with the installation.
Source: MOS document ID 1454982.1

How to list the content of a .tar file

tar -tvf yourtarfile.tar