How to install Oracle database express edition on Linux

The instructions in this blog post are validated to work on CentOS 6.4 version for installing Oracle 11g R2 database express edition. The same instructions should work OK on other Linux operating systems such as Red Hat Enterprise Linux and Oracle Enteprise Linux etc. This blog host also assumes that Oracle software is being installed for the first time on the Linux server. Change or skip some instructions if otherwise.

1) Open a new terminal

2) sudo su - root
3) mkdir /u01  (If it does not exist)
4) useradd oracle (If it does not exist)
5) groupadd dba (If the group dba does not exist)

6) usermod -g dba oracle

7) chown -R oracle:dba /u01

8) Edit /etc/oraInst.loc and add the below content.

inventory_loc=/var/opt/oracle/oraInventory
inst_group=dba

9) mkdir -p /var/opt/oracle/oraInventory

10) chown -R oracle:dba /var/opt/oracle/oraInventory

11) Install any missing Linux packages (RPMs) that are missing on the server.  The list of Linux version 6 packages required for installing 11g R2 are specified in the quick installation guide https://docs.oracle.com/cd/E11882_01/install.112/e24326.pdf

12) Download Oracle database express edition software from http://www.oracle.com/technetwork/database/database-technologies/express-edition/downloads/index.html for Linux.

13) The downloaded file name is oracle-xe-11.2.0-1.0.x86_64.rpm.zip

14) Login as root
15) unzip oracle-xe-11.2.0-1.0.x86_64.rpm.zip
16) cd Disk1
17) rpm -i oracle-xe-11.2.0-1.0.x86_64.rpm 
18) /etc/init.d/oracle-xe configure

19) ps -fu  oracle  (Verify the background processes are started for XE database instance)
20) sudo su  -  oracle  (Switch to oracle operating system user)
21) Edit /home/oracle/.bash_profile and add the below lines.

export ORACLE_HOME=/u01/app/oracle/product/11.2.0/xe
export PATH=$ORACLE_HOME/bin:$PATH
export ORACLE_SID=XE
export TNS_ADMIN=$ORACLE_HOME/network/admin

22) sqlplus ‘/ as sysdba’   (Login to the database with DBA privilege)
23) alter user hr account unlock;  (The sample HR schema is locked by default)
24) alter user hr identified by hr; (Reset the password of HR schema)

References: http://docs.oracle.com/cd/E17781_01/install.112/e18802/toc.htm#XEINL123

How to format a json file

Introduction

JSON or JavaScript Object Notation is an open standard format that uses human-readable text to transmit data objects in the form of attribute-value pairs (also referred as key/value paris). It is now considered an alternative to XML for transmitting data between a server and an application.

It is platform independent and code for parsing and generating JSON documents is available in many programming languages. Furthermore, it enjoys a lot of popularity among developers in building data sets accessed through APIs (Application Programming Interfaces). Popular examples include the Twitter API and Yelp.com API. The official Internet media type for JSON is application/json. The JSON filename extension is .json.

Problem

The Yelp.com academic data sets are available in JSON format. One can download the data sets by visiting the web page https://www.yelp.com/dataset_challenge/dataset

The file downloaded is yelp_dataset_challenge_academic_dataset.tgz. Once the contents are extracted using tar -xvf yelp_dataset_challenge_academic_dataset.tgz command, the individual .json files are available for use. 

They include yelp_academic_dataset_business.json, yelp_academic_dataset_review.json and yelp_academic_dataset_tip.json etc. Each json file contains several hundreds of json data objects, one per line. Because the key, value pairs in each of these json data objects is not indented well, it becomes tough to comprehend keys that are nested or keys that have an array of values or a combination of both. 

For example, the first JSON data object (first line) of the file yelp_academic_dataset_business.json  is stored as 

"business_id": "vcNAWiLM4dR7D2nwwJ7nCA", "full_address": "4840 E Indian School Rd\nSte 101\nPhoenix, AZ 85018", "hours": {"Tuesday": {"close": "17:00", "open": "08:00"}, "Friday": {"close": "17:00", "open": "08:00"}, "Monday": {"close": "17:00", "open": "08:00"}, "Wednesday": {"close": "17:00", "open": "08:00"}, "Thursday": {"close": "17:00", "open": "08:00"}}, "open": true, "categories": ["Doctors", "Health & Medical"], "city": "Phoenix", "review_count": 9, "name": "Eric Goldberg, MD", "neighborhoods": [], "longitude": -111.98375799999999, "state": "AZ", "stars": 3.5, "latitude": 33.499313000000001, "attributes": {"By Appointment Only": true}, "type": "business"}

A well indented JSON data object should be similar to the example in Code Listing 1 in the article http://www.oracle.com/technetwork/issue-archive/2015/15-jan/o15dba-2372211.html

Solution

1) Extract the first JSON data object in the file yelp_academic_dataset_business.json  and store it separately in business.json

2) Now run the command

cat business.json | python -m json.tool > business_one_json_document.json

3) The business_one_json_document.json file now contains the JSON data object with indented key/value pairs and therefore more readable.

{
    "attributes": {
        "By Appointment Only": true
    },
    "business_id": "vcNAWiLM4dR7D2nwwJ7nCA",
    "categories": [
        "Doctors",
        "Health & Medical"
    ],
    "city": "Phoenix",
    "full_address": "4840 E Indian School Rd\nSte 101\nPhoenix, AZ 85018",
    "hours": {
        "Friday": {
            "close": "17:00",
            "open": "08:00"
        },
        "Monday": {
            "close": "17:00",
            "open": "08:00"
        },
        "Thursday": {
            "close": "17:00",
            "open": "08:00"

       },

        "Tuesday": {

            "close": "17:00",

            "open": "08:00"

        },

        "Wednesday": {

            "close": "17:00",

            "open": "08:00"

        }

    },

    "latitude": 33.499313000000001,

    "longitude": -111.98375799999999,

    "name": "Eric Goldberg, MD",

    "neighborhoods": [],

    "open": true,

    "review_count": 9,

    "stars": 3.5,

    "state": "AZ",

    "type": "business"

}

Cloudera Quickstart VM 5.3 Apache Pig configuration

Introduction

Cloudera provides a pseudo-distributed node for working with Apache Hadoop. It is called the Cloudera Quickstart VM. While most tools in the Hadoop ecosystem such as Apache Sqoop and Apache Hive work right out of the box , Apache Pig requires some additional configuration to make it work smoothly. This blog post provides the details of such additional configuration steps.

Solution

1. Open a new Terminal.

2. su - root (Enter cloudera as the password)

3. cd /etc/pig/conf

4.

a. mv log4j.properties log4j.properties.orig (Let us make a copy of the default file)
b. cp -p log4j.properties.orig log4j.properties

5. 

a. mv pig.properties pig.properties.orig (Let us make a copy of the default file)
b. cp -p pig.properties.orig pig.properties

6. Edit log4j.properties as below

a.Replace log4j.logger.org.apache.pig=info, A with the below
 log4j.logger.org.apache.pig=error, A

b. Then add a new line log4j.logger.org.apache.hadoop=error, A

7. Edit pig.properties as below

a. Uncomment (remove the #) the line log4jconf=./conf/log4j.properties if it is already commented and let the line start with no blank spaces.

b. Replace the line starting with #clustername with quickstart.cloudera:50010

quickstart.cloudera:50010 is the Hadoop cluster name in the Quickstart VM. You can find this information by running the hdfs dfsadmin -report command.

8. chmod -R o+w /etc/pig/conf.dist

9. cp -p /usr/lib/hadoop/lib/slf4j-api-1.7.5.jar /usr/lib/hive/lib

Conclusion

The above steps will help avoid the following errors when Pig is run in interactive mode using the Grunt shell.

ls: cannot access /usr/lib/hive/lib/slf4j-api-*.jar: No such file or directory

WARN pig.Main: Cannot write to log file: /etc/pig/conf.dist/pig_1435724561990.log

ERROR org.apache.pig.tools.pigstats.SimplePigStats - ERROR: org.apache.hadoop.yarn.exceptions.ApplicationNotFoundException: Application with id 'application_1435707575650_0004' doesn't exist in RM.

A client error (AuthFailure) occurred: AWS was not able to validate the provided access credentials

Problem

Amazon Web Services (AWS) offers both the web-based management console as well a command line interface (CLI). The other day we were use the CLI on an EC2 instance running Red Hat Enterprise Linux Server release 6.4 operating system. But even after installing and configuring the CLI using the AWS CLI user guide, every CLI command was failing with the "A client error (AuthFailure) occurred..." error. For example, the basic command "aws ec2 describe-instances --region us-west-2" failed with the below error.

A client error (AuthFailure) occurred when calling the DescribeInstances operation: AWS was not able to validate the provided access credentials.

Solution

The date command returned an incorrect time. Whereas the actual time is Fri May 22 23:33:18 EDT 2015, it returned Sat May 23 03:33:18 EDT 2015.  We then found that the NTP daemon was not running (Network Time Protocol). Once we started the ntpd deamon, the "aws ec2 describe-instances --region us-west-2" worked and returned the expected output in the AWS CLI default JSON format. We followed the AWS user guide on how to start the ntpd deamon successfully.

1. ntpstat
Unable to talk to NTP daemon. Is it running?

2. sudo service ntpd start
Starting ntpd:                                             [  OK  ]

3. sudo chkconfig ntpd on

4. ntpstat
unsynchronised
   polling server every 64 s

5. date

The date command then returned the correct time.

6. aws ec2 describe-instances --region us-west-2

Finally, the aws ec2 command above returned the output successfully.

How to install and setup Oracle 12c RAC on PC using VirtualBox

Introduction

Are you spending many hours in figuring out how to install and setup Oracle 12c RAC cluster on your PC ? DBA University will help you perform a successful installation and setup of Oracle 12c on your PC using Oracle VirtualBox hypervisor if you register for our comprehensive training course in Oracle 12c ASM, RAC and Data Guard topics.  

This course is conducted by Michelle Malcher. Michelle is a well experienced Oracle Database Administrator. She is a well known author of several Oracle Press books. Also, she is an Oracle ACE Director (only a few in the world are recognized as ACE Director by Oracle Corporation) and a noted contributor to Oracle Magazine.

Course Timings

1) 40 hours course in 5 weeks.

2) Evenings - Sun, Mon, Tue and Thu  - 7 pm Central Time to 9 pm Central Time.

3) Online Training, but very interactive with whiteboard teaching methodology.

Course Details and Lab Work

1) We will provide you the VM that will help in a hassle-free and successful 2 Node RAC cluster on Linux operating systems using Oracle VirtualBox.  We have taken care of all the details and in just a week, you will have a working 2 Node RAC cluster on your PC. 

2) We will provide detailed training material (eBook) that will list all the hardware and software pre-requisites, network setup tasks and screenshots for a successful Oracle 12c Grid Infrastructure and Oracle 12c RDBMS software installation on the 2 Node cluster.

3) We also have separate lab exercises on Oracle 12c ASM (Automatic Storage Management) that includes how to partition and configure disks for ASM usage using the Linux ASMLib utility, ASM mirroring and how to replace failed disks in an ASM disk group. 

4) You will also become very strong in learning how to setup and maintain an Oracle 12c Data Guard environment.

Course Brochure and Registration

1) Click here to see the course topics.

2) Click here for a FREE DEMO session  (Name and Email only).

3) Click here to register for the online training course.

4) Fee is $799 and paid online using the above registration link.

Big Data with Hadoop Training

Introduction

We have some exciting news for you. We are starting the Big Data with Hadoop training program and Srini Ramineni will be the faculty for this course. Srini Ramineni is the founder of DBA University and has rich experience in the IT industry in USA managing both relational databases as well as Big Data with Hadoop environments. He also has completed a graduate degree credit hour program in Big Data using Hadoop at a reputed university in USA.

The training topics include the Hadoop core components viz. The Hadoop File System (HDFS) and the Map Reduce computation paradigm.  All the other major sub projects of the Hadoop solution such as Apache Sqoop, Hive, Pig, Impala, Flume and Spark are also included in this training course.  Most of the topics have lab exercises too.

Course Highlights

1) 6 and half weeks course with 40 hours total duration.

2) Training will contain lab work on both single node machine as well as a Hadoop cluster (multi-node).

3) Evenings - Sun, Mon, Tue  - 7 pm Central Time to 9 pm Central Time

4) DBA University's training material will be provided.

5) Click here for a FREE DEMO session  (Name and Email only)

6) Click here to register for the actual training course.

Links and Resources

1) Click here to know more about the course topics.

2) Click here for a FREE DEMO session  (Name and Email only)

3) Click here to register for the actual training course.

How to fix VNC Viewer black screen

Introduction

Have you seen your VNC Viewer showing a black screen intermittently ?  We have a fix for it. This issue has been occurring in our lab servers for a few students intermittently since the past few months on Oracle Linux server 6.5 release.

Problem

The VNC Viewer desktop background turns into a full black screen intermittently. It does not happen all the time and one of our students observed that this issue happens consistently when she  hovers her mouse on the VNC Config icon on the top left hand corner. This issue happens even if this icon is minimized. This observation is correct.

Solution

A workaround is to just close the above VNC config icon instead of minimizing it. But the permanent solution is to let the vncconfig deamon run in nowin mode (no window icon). Our vncserver service is owned by oracle operating system account. 

a) Login to the server using a different protocol such as ssh on port 22.

b) cd /home/oracle/.vnc

b) Edit xstartup file and replace vncconfig -iconic & with vncconfig -nowin &

c) Now bounce the vncserver service using the below commands

vncserver -kill :1.0
vncserver
export DISPLAY=:1.0
xhost +

Conclusion

The -nowin parameter will make the vncconfig functionality stay intact, but without the desktop icon. The actual cause of the problem could be due to an issue with the vnc-server RPM itself, specifically tigervnc-server-module 1.1.0-8.el6_5.x86_64.