Oracle 10g RAC On Windows 2003 Using VMware Server

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[Courtesy: http://www.oracle-base.com]

This article describes the installation of Oracle 10g release 2 (10.2.0.1) RAC on Windows 2003 Server Standard Edition using VMware Server with no additional shared disk devices.

Introduction

One of the biggest obstacles preventing people from setting up test RAC environments is the requirement for shared storage. In a production environment, shared storage is often provided by a SAN or high-end NAS device, but both of these options are very expensive when all you want to do is get some experience installing and using RAC. A cheaper alternative is to use a FireWire disk enclosure to allow two machines to access the same disk(s), but that still costs money and requires two servers. A third option is to use VMware Server to fake the shared storage.
Using VMware Server you can run multiple Virtual Machines (VMs) on a single server, allowing you to run both RAC nodes on a single machine. In additon, it allows you to set up shared virtual disks, overcoming the obstacle of expensive shared storage.
Before you launch into this installation, here are a few things to consider.

• The finished system includes the host operating system, two guest operating systems, two sets of Oracle Clusterware, two ASM instances and two Database instances all on a single server. As you can imagine, this requires a significant amount of disk space, CPU and memory. To complete this installation I used a dual 3.0G Xeon server with 4G of memory.
  
• This procedure provides a bare bones installation to get the RAC working. There is no redundancy in the Clusterware installation or the ASM installation. To add this, simply create double the amount of shared disks and select the "Normal" redundancy option when it is offered. Of course, this will take more disk space.
  
• During the virtual disk creation, I always choose not to preallocate the disk space. This makes virtual disk access slower during the installation, but saves on wasted disk space.
  
• This is not, and should not be considered, a production-ready system. It's simply to allow you to get used to installing and using RAC.

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Oracle 10g RAC Versus DataGuard For High Availability

Oracle 10g RAC Versus DataGuard For High Availability

[courtesy: http://www.iheavy.com]

Oracle has two very different technologies, each with it's own strengths and weaknesses that implement high availability solutions. In choosing between the two technologies, it's important to factor in the relevant risks, both small and large, to put the entire picture into perspective.

Two Alternatives
RAC or Real Application Clusters, is essentially an always-on solution. You have multiple instances or servers accessing the same database on shared storage in your network. With existing technology limitations, in practical terms, these different servers must be on the same local network, in the same datacenter.

Oracle's DataGuard technology, formerly called Standby database in previous versions, provides a rolling copy of your production database. The standby database is started in read-only mode, constantly receiving change data, sent over from the production database, keeping it always in sync at all times, and at most only a few minutes behind. Were the production server to fail, that server could take over in less than the time the DNS change or IP swap would take. What's more the standby copy can be at another datacenter, or on another continent!

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SQL Alias

SQL Aliases are defined for columns and tables. Basically aliases is created to make the column selected more readable.
For Example: To select the first name of all the students, the query would be like:

Aliases for columns:

SELECT first_name AS Name FROM student_details;
or
SELECT first_name Name FROM student_details;

In the above query, the column first_name is given a alias as 'name'. So when the result is displayed the column name appears as 'Name' instead of 'first_name'.

Learning SQL

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SQL Commands

SQL SELECT

SQL Alias

SQL WHERE

SQL Operators

SQL Logical Operators

SQL LIKE, IN

SQL ORDER BY

SQL Group Functions

SQL GROUP BY

SQL HAVING

SQL INSERT

SQL UPDATE

SQL DELETE

SQL CREATE TABLE

SQL ALTER TABLE

SQL Integrity Constrain

SQL JOINS

SQL VIEWS

SQL Subquery

SQL Indexes

SQL GRANT, REVOKE

Oracle Functions

SQL SELECT

 

The most commonly used SQL command is SELECT statement. The SQL SELECT statement is used to query or retrieve data from a table in the database. A query may retrieve information from specified columns or from all of the columns in the table. To create a simple SQL SELECT Statement, you must specify the column(s) name and the table name. The whole query is called SQL SELECT Statement.

Syntax of SQL SELECT Statement:

SELECT column_list FROM table-name
[WHERE Clause]
[GROUP BY clause]
[HAVING clause]
[ORDER BY clause];


• table-name is the name of the table from which the information is retrieved.
  
• column_list includes one or more columns from which data is retrieved.
  
• The code within the brackets is optional.

SQL Commands

 

SQL commands are instructions used to communicate with the database to perform specific task that work with data. SQL commands can be used not only for searching the database but also to perform various other functions like, for example, you can create tables, add data to tables, or modify data, drop the table, set permissions for users. SQL commands are grouped into four major categories depending on their functionality:

• Data Definition Language (DDL) - These SQL commands are used for creating, modifying, and dropping the structure of database objects. The commands are CREATE, ALTER, DROP, RENAME, and TRUNCATE.
• Data Manipulation Language (DML) - These SQL commands are used for storing, retrieving, modifying, and deleting data. These commands are SELECT, INSERT, UPDATE, and DELETE.
• Transaction Control Language (TCL) - These SQL commands are used for managing changes affecting the data. These commands are COMMIT, ROLLBACK, and SAVEPOINT.
• Data Control Language (DCL) - These SQL commands are used for providing security to database objects. These commands are GRANT and REVOKE.