Step by Step guide to Install Oracle 11g on Ubuntu VM

After downloading the Ubuntu VMWare image, there were few more quirks to settle.
I had to install NFS and SSH on the machine to make it accessible by ssh from Windows.

Following are the commands:
sudo apt-get install openssh-server openssh-client

sudo apt-get install nfs-kernel-server nfs-common portmap

One of the forums that helped were:
http://ubuntuforums.org/archive/index.php/t-492772.html

Now I setup the samba share on this machine

sudo aptitude install samba

https://help.ubuntu.com/community/SettingUpSamba

After installing the samba, create a directory on the FS which you want to share with Windows or other systems.
Then edit /etc/samba/smb.conf and add these lines to the end

[share_name]
        comment = Share to Linux
        path = /home/user/winshare
        guest ok = yes
        writeable = yes

You can use the following commands to restart the services if needed:
/etc/init.d/nfs-common restart
/etc/init.d/samba restart

Following is a suggested helpful link:
http://www.howtogeek.com/howto/ubuntu/create-a-samba-user-on-ubuntu/

Process to install the Oracle on Ubuntu starts

This page is particularly helpful and is worth reading every bit:
http://www.pythian.com/blogs/654/installing-oracle-11g-on-ubuntu-linux-710-gutsy-gibbon

It mentions the packages that need to be updated before Oracle Installation.

apt-get update
apt-get upgrade (This would update the packages from the internet and will take sometime)

Anyways follow step by step the instructions in the above link to complete the installation.

At some point of time, you will encounter insufficient disk space in Linux due to which you cannot install Oracle.
To add more disk space to the Linux VM, follow the link below
http://www.matttopper.com/?p=25

I allocated a 20GB SCSI HD to Linux VM and split it into 3 partitions. The FSTAB entries are:
/dev/sdb1 /u01 ext3 defaults 1 1
/dev/sdb2 /oradata ext3 defaults 1 1
/dev/sdb3 /data ext3 defaults 1 1

Also, the Oracle installer needs a GUI. So, you need an X-Server (like eXceed) to complete the installation.
Simply on command prompt, set DISPLAY

For bash- > export DISPLAY=ExceedHostIP:0.0

And then start Exceed on Windows and connect to the IP address of the VM linux. Try 3-4 times to connect as it may error out.

If you get a timeout error, ignore the message and press nothing. Continue with Installation and complete the post-installation steps in
http://www.pythian.com/blogs/654/installing-oracle-11g-on-ubuntu-linux-710-gutsy-gibbon

Good Luck

Installing APEX on Oracle 11g from Database Troubleshooting

I installed Oracle 11g on Oracle Linux from a VM Image. So I am good with Oracle Installation.

Now my interest is to use APEX on this database.

I followed the instructions on the following page:
http://download.oracle.com/docs/cd/E10513_01/doc/install.310/e10496/db_install.htm#CBHCDBAB

After the installation is complete and I tried to access
http://localhost:8080/apex/apex_admin, I kept getting username/password for xdb account.
I tried unlocking the account xdb and anonymous using
alter user xdb account unlock;
alter user anonymous account unlock;

It didnt work.

If it works for you then, you will be able to access the site. That site requires admin as username.
You will need to change the password for this user in the database by executing the following command:
sql> @apxxepwd.sql <admin123>
This command is found in $ORACLE_HOME/apex

Then I tried executing apex_epg_config script found in
/ora/db/11.1.0/apex

It asks for a parameter. This parameter should be /ora/db/11.1.0
eg.
sql> @apex_epg_config $ORACLE_HOME

It basically loads the apex images to the database. Instructions for executing this script is not well-documented.

But still the problem remains the same. I am not able to access the website.

Now I stop the listener.
$ lsnrctl stop

and then
$lsnrctl start

Copyright (c) 1991, 2007, Oracle. All rights reserved.

Starting /ora/db/11.1.0/bin/tnslsnr: please wait...

TNSLSNR for Linux: Version 11.1.0.6.0 - Production
System parameter file is /ora/db/11.1.0/network/admin/listener.ora
Log messages written to /ora/diag/tnslsnr/oracle2go/listener/alert/log.xml
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=oracle2go.us.oracle.com)
(PORT=1521)))
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1521)))

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=oracle2go.us.oracle.com)
(PORT=1521)))
STATUS of the LISTENER
------------------------
Alias LISTENER
Version TNSLSNR for Linux: Version 11.1.0.6.0 - Production
Start Date 03-FEB-2009 08:26:18
Uptime 0 days 0 hr. 0 min. 0 sec
Trace Level off
Security ON: Local OS Authentication
SNMP OFF
Listener Parameter File /ora/db/11.1.0/network/admin/listener.ora
Listener Log File /ora/diag/tnslsnr/oracle2go/listener/alert/log.xml
Listening Endpoints Summary...
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=oracle2go.us.oracle.com)(PORT=1521))
)
(DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1521)))
The listener supports no services
The command completed successfully

Then waited for 5 minutes. Somehow it didnt work for me the next instant. I think it takes some time to refresh.

Now I can access the
http://localhost:8080/apex website.

The key is to restart the listener after unlocking the xdb account.

There is another page that I hit while searching for the solutions to APEX installation:
http://www.uaex.edu/srea/Application_Express_Installation.htm

Funny Matrix Windows XP Video

I stumbled upon this hilarious Matrix and Windows XP video

BSNL DNS Internet access disrupted yet Skype is functional

Users of BSNL might encounter this issue quite often.
No website can be opened using Internet Explorer, Firefox, Chrome, etc. Yahoo Messenger wont work too.
But Skype works without a problem.

The reason :
The DNS server of BSNL doesn't work for some reason. Each website that you try to access eg. www.neooug.org gets translated to an IP address. This translation is provided by the DNS server. And if the DNS server is unavailable, your computer doesn't get back an IP address and hence you are unable to access the website.
But if you try to access the website using the IP address directly ( On command prompt : ping www.yahoo.com
gives you
H:\>ping www.yahoo.com

Pinging www.yahoo-ht3.akadns.net [69.147.76.15] with 32 bytes of data:

Reply from 69.147.76.15: bytes=32 time=10ms TTL=54
Reply from 69.147.76.15: bytes=32 time=10ms TTL=54
Reply from 69.147.76.15: bytes=32 time=10ms TTL=54
Reply from 69.147.76.15: bytes=32 time=16ms TTL=54

Ping statistics for 69.147.76.15:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 10ms, Maximum = 16ms, Average = 11ms

So, if you put http://69.147.76.15/ in the web-browser, you can access the website. But its just not possible to get the IP address if the DNS server is down.
In case of Skype, this issue doesn't arise because skype connects using the IP address.

Solution:
Open the Network Connection/Wireless connection properties on your computer. Open Properties for TCP/IP and change the "Obtain DNS server address automatically" to "Use the following DNS Server addresses"

208.67.222.222

and 

208.67.220.220

These addresses are provided by http://www.opendns.com

You can also configure your wireless router to use this address so that you don't have to configure each machine on your network to set this DNS information.

More instructions can be found at

https://www.opendns.com/smb/start

Oracle External Table error for Subquery

Oracle 10g 10.2.0.4 and below (BUG 5600425 at metalink)

Oracle says that the bug is fixed in 10.2.0.4 but it is not.

So, if you are trying to access an external table using a subquery and a NOT IN clause, the query may error out due to field formatting errors. Even if you use SKIP 1 for the external table definition and your external file has a header row, the following query may return a SQL Loader error.

      DELETE FROM cfgview
        WHERE cfgviewid NOT IN (SELECT view_id
                                FROM vw_ext_acc_configview);

An alternative is to use

      DELETE FROM cfgview cv
        WHERE NOT EXISTS (SELECT NULL
                 FROM vw_ext_acc_configview vecv
                WHERE vecv.view_id = CV.cfgviewid); 

Oracle Subquery bug - Test each subquery individually

Here arises the importance of unit testing each subquery individually. Consider the scenario below:

I have this code:

 DELETE FROM cfgview
        WHERE cfgviewid NOT IN (SELECT cfgviewid
                                FROM vw_ext_acc_configview);

The inner subquery if executed alone, returns an error because the columnname cfgviewid doesn't exist.

But if you execute the full query, it returns successfully and deletes 0 rows.

So, this implies that you need to unit test each query before adding it as a subquery.

Oracle Enterprise Manager 10g Job Scheduler Configuration Problem Resolution for Solaris

Oracle Enterprise Manager 10g is a powerful tool that comes with many administrative features which make database management much more simpler.
It has an inbuilt job scheduler that lets you schedule jobs. Its not a very feature rich scheduler but still does quite a lot considering the fact that it is free with Oracle's License.

I am outlining a configuration problem that may save some time to diagnose:
If a shell script or a Java program is executed using OEM under the credentials of a user who doesnt belong to the Oracle user group on Solaris, it fails with the following error:

Shell script :

/bin/sh: cannot determine current directory
or

shell-init: could not get current directory: getcwd: cannot access parent directories: Permission denied

Java Proram :

Error occurred during initialization of VM
java.lang.Error: Properties init: Could not determine current working directory

This is due to permission lacking on the directory where the OEM agent is installed
/u01/app/oracle/product/agent10g/sysman/emd

Check the permissions on this directory.
drwxr-x--- 6 oracle dba 512 May 12 13:40 emd

Change the permissions to
drwxr-xr-x 6 oracle dba 512 May 12 13:40 emd

I believe that OEM's working directory is the above location and since the underlying user doesnt have access to this directory, hence all the programs error out.