Oracle Database Administration for Microsoft SQL Server DBAs part 10 docx

72 Oracle Database Administration for Microsoft SQL Server DBAs... In SQL Server, there could be several databases for the instance, so there can be several different schemas in a databa

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There are some shared areas such as /tmp that will cause issues to running or installing Oracle software if they fill up So carefully place files here, or be sure to purge out old installation logs that are placed here There are also system areas which can normally be viewed but not modified If sharing the server it would be important to make sure that changes to these system areas are communicated, or discussed first The Oracle user does not need full permissions or root access to view the configuration information, but being able to view the information is useful to verify the configurations

72 Oracle Database Administration for Microsoft SQL Server DBAs

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Database Definitions

and Setup

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I n the previous chapter, we walked through installing the Oraclesoftware The server should now be configured for Oracle, and

the required components installed The advantage of installing the software by itself first is that if there are any issues with the

configuration, the database doesn’t need to be dropped and re-created each time It is very easy to launch the Oracle configuration assistants after the installation

This chapter covers the next steps after the software is installed The Database Configuration Assistant will guide you through the creation of the database We will look at some of the configuration options, as well as how

to use templates and scripts

Security is a big part of database setup We already talked about security

at the operating system level, and there will be more at the application level Here, we will look at server and schema security These various levels

of security will help you to achieve a more secure system

Before we get into the details of database setup, let’s clarify some of the terminology, which also will reveal some of the differences between the SQL Server and Oracle platforms

Servers, Databases, Instances,

and Schemas

As a DBA, you are certainly familiar with database terminology The problem

is that on different database platforms, the terms don’t always mean the same thing Consider that even general terms can take on various meanings

A generic definition ofdatabase is “data and information that is collected together for the ability to access and manage.” The term server could refer

to the actual server hardware or to the database server

A SQL Server database is not the same as an Oracle database The SQL Server database has users allocated to it, its own system objects, and its own datafiles In Oracle, the termschema is more closely related to the SQL Server database Schemas can own the objects in both environments In SQL Server, there could be several databases for the instance, so there can

be several different schemas in a database In Oracle, there are multiple schemas in a database, including the system schemas

The Oracle schema is a collection of objects, and it could have its own tablespace allocated to it on the datafiles for the database The user schema usually does not contain system objects, because the system objects are in their own schema There is only one set of system objects for each database

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server, unlike with SQL Server, which has different layers of system objects

at the server level and the database level Also, there are no users inside the Oracle schemas, because they are only at the server level

The Oracle database is almost like the instance level for SQL Server The Oracle database is the overall group of datafiles and system information

The Oracle software, memory structures, and processes make up an

instance There is one Oracle database for the instance In a clustered

environment, there can be multiple instances that all point to one database

on a shared disk

Database owner is another term that doesn’t really exist in Oracle

Typically, the termschema owner is used

Figure 4-1 shows some of these terms and how they apply in the different database environments Understanding the differences will help you to see

where the services, processes, and datafiles play their parts, and how the

different levels interact and handle processes within the various structures

FIGURE 4-1. Comparing SQL Server and Oracle terminology

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To clarify how these terms are used in the different database systems, let’s look at some naming examples We’ll use the domain us.demo.com and a server intended to support a human resources (HR) application, with information about payroll, benefits, employees, and so on Table 4-1 shows the names for a single server, and Table 4-2 shows the names for a clustered environment

NOTE

It is helpful to name a server with a department

or functional name, so that it’s easy to

recognize the purpose of the server

Database Name Definitions

The following are used to identify Oracle databases:

■ SID System identifier—database or instance name The SID

and hostname uniquely identify an Oracle database (similar to a SQL Server instance name)

■ Database name Unique name, normally the same as a SID.

■ Global database name Database name plus the domain (such

as us.demo.com)

■ DBID Unique database identifier that is assigned by the

system This information is found in v$database

The SQL Server SID and Oracle SID are two very different animals

A SQL Server SID is a security identifier, which is the system-assigned key to a login, as seen in the syslogins table The Oracle SID is the database name that the database creator chooses for the database or instance

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SQL Server Setup Versus

Oracle Setup

With SQL Server, we tend to install an instance with the software, which

creates the service and allocates the memory The system databases are also created, with some of the defaults being set up in the model database for

other databases SQL Server databases can be a different collation and a

Name SQL Server Oracle

orasrvhr02v

PRODHR02(SID) Database payroll_db, benefits_db,

hr_db, employee_db

PRODHR

TABLE 4-2. Clustered Environment Naming Examples

Name SQL Server Oracle

Server (Windows

or Linux)

sqlsrvhr01.us demo.com

orasrvhr01.us demo.com Instance Local server or named instance:

PRODHR

PRODHR (SID)

Database payroll_db, benefits_db,

hr_db, employee_db

PRODHR (global database name PRODHR.us.demo.com) Schema dbo PAYROLL, BENEFITS,

HR, EMPLOYEE Database server sqlsrvhr01\PRODHR orasrvhr01\PRODHR

TABLE 4-1. Database Server Naming Examples

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different version than the server For example, a server can have the

collation of SQL_Latin1_General_CP1_CI_AS, and a new database can be created with a collation of French_CI_AI

SELECT

SERVERPROPERTY('ProductVersion') AS ProductVersion,

SERVERPROPERTY('Collation') AS Collation;

ProductVersion Collation

10.0.1600.22 SQL_Latin1_General_CP1_CI_AS

Create database Example1

collate French_CI_AI;

select name, collation_name, compatibility_level

from sys.databases;

name collation_name compatibility_level master SQL_Latin1_General_CP1_CI_AS 100

tempdb SQL_Latin1_General_CP1_CI_AS 100

model SQL_Latin1_General_CP1_CI_AS 100

msdb SQL_Latin1_General_CP1_CI_AS 100

test1 SQL_Latin1_General_CP1_CI_AS 100

example1 French_CI_AI 100

A SQL Server database gets a different version by attaching a database from a different version The upgrade of the database can be done after attaching it to the server, but it can also exist as a different version than the server version The following example shows the compatibility level from SQL Server 2005 on a SQL Server 2008 instance

select name, collation_name, compatibility_level

from sys.databases;

name collation_name compatibility_level master SQL_Latin1_General_CP1_CI_AS 100

tempdb SQL_Latin1_General_CP1_CI_AS 100

model SQL_Latin1_General_CP1_CI_AS 100

msdb SQL_Latin1_General_CP1_CI_AS 100

mmtest SQL_Latin1_General_CP1_CI_AS 90

With Oracle, the software is installed, and then we set up the database with character sets, system information, and version The database and instance have the same character set The Oracle schemas do not have the option for changing the character set The software components installed are the versions that are used for the database server This demonstrates that the Oracle database has the system objects and keeps the system-level options

at the database level

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Creating Databases

Oracle provides the Database Configuration Assistant (DBCA) to help

you create new databases Other assistants are available for configuring

upgrades (DBUA) and Oracle Enterprise Manager (EMCA) You can also

use database scripts and templates to re-create databases with the same

configuration We’ll start by walking through the DBCA

Using the DBCA

The DBCA will create the instance parts, which are the processes and the

datafiles for the database It will set up the memory structures

Launch the DBCA from the ORACLE_HOME\bin directory Figure 4-2

shows step 1 of the assistant, where you select to create a database

FIGURE 4-2. Selecting to create a database with the DBCA

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As you step through the assistant, you name the database and accept default values or change them as necessary Here are some points to keep

in mind:

■ Choose a unique name for the database It is possible to create

a database with the same name as an existing database if it is on another server You might do this if you are planning a move or

an upgrade that is not in place The global name just includes the domain name for the environment

■ The generic templates are good starting points for creating a database You can choose from a data warehousing template, a general transaction database, or a custom shell to start, as shown

in Figure 4-3 The transaction processing and data warehouse templates have the option to set up the datafiles The custom template starts without the datafiles, which can be added later

FIGURE 4-3. Choosing a database template

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■ Oracle Enterprise Manager (OEM) and the dbconsole process will be set up to manage a couple of the regular maintenance jobs Having these steps here is just a convenience, as these can be set up

separately at another time

■ The variables set for ORACLE_HOME and ORACLE_BASE will be used for where the datafiles and various alert log directories are set up

■ You can select ASM and add disk groups for this database or for

using the file systems, and changes can be made to where the files

are created

■ As part of the database creation, the SYSTEM, UNDO, and TEMP

tablespaces are created A user tablespace can also be configured

■ You can specify locations for the database files, as shown in Figure 4-4

FIGURE 4-4. Choosing database file locations with the DBCA

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