OCA /OCP Oracle Database 11g A ll-in-One Exam Guide- P13 doc

It is not large in terms of the practicalities creating a database can be quick and simple—a single two-word command will do it, and it may take less than ten minutes, but there are many

3 If you are not working on the console machine, set your DISPLAY variable to point to an X Window server on the machine on which you are working In the illustration, this is 10.0.0.12:0.0

4 Launch the OUI by running the runInstaller shell script from the root of the installation media In the example, the installation media has been copied into the directory /home/db11g/db11g_dvd

5 The first OUI window will appear, as in the illustration that follows:

A Select the Basic Installation radio button

B Specify the Oracle Base as the directory created in Step 2 The Oracle Home will default to an OFA-compliant name beneath it

C Select the Enterprise Edition installation type

D Select dba as the Unix DBA group

E De-select the option to create a database

F Click NEXT

6 If this is the first Oracle install on the machine, the next window will prompt for the location of the OUI inventory Be sure to specify a directory to which the db11g user has write permission

7 The OUI will then perform its prerequisite checks If they pass, click NEXT to continue If any fail, take note and fix them if possible Then use the RETRY

button to rerun the test If the check really cannot be fixed, you can click NEXT

to proceed anyway at your own risk

8 The next window will be a summary of what the OUI is going to do Click

NEXT, and it will do it This should take twenty minutes or so (highly variable, depending on the machine)

9 Toward the end of the install, the window shown in the illustration that

follows will appear This prompts you to run two scripts as the root user: the

orainstRoot.sh script that will write the /etc/oraInst.loc file, and

the root.sh script that adjusts permissions on files in the new Oracle home

If this is not the first time the OUI has run on the machine, there will not be

a prompt for orainstRoot.sh Run the script(s) as root from an operating

system prompt (accept defaults for any prompts) and then click OK

10 The installer will return a message stating that “The installation of Oracle

Database 11g was successful.” Congratulations! Click EXIT

Create a Database by Using the Database

Configuration Assistant

This one OCP examination objective is in fact a large task, comprising several steps It is

not large in terms of the practicalities (creating a database can be quick and simple—a

single two-word command will do it, and it may take less than ten minutes), but there

are many prerequisite concepts you should understand:

• The instance, the database, and the data dictionary

• Using the DBCA to create a database

• The instance parameter file

• The CREATE DATABASE command

• Post-creation scripts

• The DBCA’s other functions

The Instance, the Database, and the Data Dictionary

An Oracle server consists of an instance and a database; the two are separate, but connected The instance comprises memory structures and processes, stored in your machine’s RAM and executing on its CPU(s); its existence is transient; it can be started and stopped The database comprises files on disk; once created, it persists until it is deleted Creating an instance is nothing more than building the memory structures and starting the processes Creating a database is done by the instance as a once-off operation, and the instance can then open and close it many times subsequently The database is inaccessible without the instance

Within the database there is a set of tables and other segments called the data

dictionary The data dictionary describes all the logical and physical structures in the

database, including all the segments that store user data

The process of database creation establishes the bare minimum of physical structures needed to store the data dictionary, and then creates the data dictionary within them

An instance is defined by an instance parameter file The parameter file contains

directives that define how the instance should be initialized in memory: the size of the memory structures, and the behavior of the background processes After building the

instance, it is said to be in no mount mode In no mount mode, the instance exists but

has not connected to a database Indeed, the database may not even exist at this point All parameters, either specified by the parameter file or implied, have default values, except for one: the parameter DB_NAME The DB_NAME parameter names the database

to which the instance will connect This name is also embedded in the controlfile The CONTROL_FILES parameter points the instance to the location of the controlfile This parameter defines the connection between the instance and the database When the instance reads the controlfile (which it will find by reading the CONTROL_FILES

parameter) if there is a mismatch in database names, the database will not mount In

mount mode, the instance has successfully connected to the controlfile If the controlfile

is damaged or nonexistent, it will be impossible to mount the database The controlfile is small, but vital

Within the controlfile, there are pointers to the other files (the online redo logfiles and the datafiles) that make up the rest of the database Having mounted the database,

the instance can open the database by locating and opening these other files An open

database is a database where the instance has opened all the available online redo logfiles and datafiles Also within the controlfile, there is a mapping of datafiles to tablespaces This lets the instance identify the datafile(s) that make(s) up the SYSTEM tablespace within which it will find the data dictionary The data dictionary lets the instance resolve references to objects referred to in SQL code to the segments in which they reside, and work out where, physically, the objects are

The creation of a database server must therefore involve these steps:

• Create the instance

• Create the database

• Create the data dictionary

In practice, the steps are divided slightly differently:

• Create the instance

• Create the database and the data dictionary objects

• Create the data dictionary views

The data dictionary as initially created with the database is fully functional but

unusable It has the capability for defining and managing user data but cannot be

used by normal human beings because its structure is too abstruse Before users (or

DBAs) can actually use the database, a set of views must be created on top of the data

dictionary that will render it understandable by humans

The data dictionary itself is created by running a set of SQL scripts that exist in the

ORACLE_HOME/rdbms/admin directory These are called by the CREATE DATABASE

command The first is sql.bsq, which then calls several other scripts These scripts

issue a series of commands that create all the tables and other objects that make up

the data dictionary

The views and other objects that make the database usable are generated by

additional scripts in the ORACLE_HOME/rdbms/admin directory, prefixed with “cat”

Examples of these are catalog.sql and catproc.sql, which should always be

run immediately after database creation There are many other optional “cat” scripts

that will enable certain features—some of these can be run at creation time; others

might be run subsequently to install these features at a later date

Using the DBCA to Create a Database

These are the steps to follow to create a database:

1 Create a parameter file and (optionally) a password file

2 Use the parameter file to build an instance in memory

3 Issue the CREATE DATABASE command This will generate, as a minimum,

a controlfile; two online redo logfiles; two datafiles for the SYSTEM and

SYSAUX tablespaces; and a data dictionary

4 Run SQL scripts to generate the data dictionary views and the supplied

PL/SQL packages

5 Run SQL scripts to generate the objects used by Enterprise Manager Database

Control, and any other database options chosen to be enabled

On Windows systems, there is an additional step because Oracle runs as a Windows

service Oracle provides a utility, oradim.exe, to assist you in creating this service

These steps can be executed interactively from the SQL*Plus prompt or through a

GUI tool, the Database Configuration Assistant (DBCA) Alternatively, you can automate

the process by using scripts or start the DBCA with a response file

Whatever platform you are running on, the easiest way to create a database is

through the DBCA You may well have run this as part of the installation: OUI can

launch the DBCA, which prompts you and walks you through the whole process It creates a parameter file and a password file and then generates scripts that will start the instance; create the database; and generate the data dictionary, the data dictionary views, and Enterprise Manager Database Control Alternatively, you can create the parameter file and password file by hand, and then do the rest from a SQL*Plus session Many DBAs combine the two techniques: use the DBCA to generate the files and scripts, and then look at them and perhaps edit them before running them from SQL*Plus

The DBCA is written in Java—it is therefore the same on all platforms On Unix, you run the DBCA on the machine where you wish to create the database, but you can launch and control it from any machine that has an X server to display the DBCA windows This is standard X Window System—you set an environment variable DISPLAY to tell the program where to send the windows it opens For example,

export DISPLAY=10.10.10.65:0.0

will redirect all X windows to the machine identified by IP address 10.10.10.65, no matter which machine you are actually running the DBCA on

To launch the DBCA on Windows, take the shortcut on the Start menu The navigation path will be

1 Start

2 Programs

3 Oracle – OraDB11g_home3

4 Configuration and Migration Tools

5 Database Configuration Assistant

Note that the third part of the path will vary, depending on the name given to the Oracle Home at install time

To launch the DBCA on Linux, first set the environment variables that should always be set for any Linux DBA session: ORACLE_BASE, ORACLE_HOME, PATH, and LD_LIBRARY_PATH This is an example of a script that will do this:

export ORACLE_BASE=/u02/app/db11g

export ORACLE_HOME=$ORACLE_BASE/product/11.1.0/db_1

export PATH=$ORACLE_HOME/bin:$PATH

export LD_LIBRARY_PATH=$ORACLE_HOME/lib:$LD_LIBRARY_PATH

Note that the Base and Home will vary according to choices made at install time

To launch the DBCA, run the dbca shell script, located in the $ORACLE_HOME/bin directory

TIP Be sure to have the $ORACLE_HOME/bin directory at the start of

your search path, in case there are any Linux executables with the same name

as Oracle executables A well-known case in point is rman, which is both an Oracle tool and a SUSE Linux utility

Remember that (with one exception) every choice made at database creation time

can be changed later, but that some changes are awkward and may involve downtime

It is not therefore vital to get everything right—but the more right it can be, the better

If the database to be created is going to use Enterprise Manager Database Control,

there is an additional step that should be carried out before launching the DBCA:

configuring a database listener This requirement is because Database Control always

connects to its database through a listener, and the DBCA checks whether one is

available The configuration is a simple task, described in detail in Chapter 4 For

now, do this with the Net Configuration Assistant, accepting defaults all the way

To launch the Net Configuration Assistant on Windows, take the shortcut on the

Start menu The navigation path will be

1 Start

2 Programs

3 Oracle – OraDB11g_home3

4 Configuration and Migration Tools

5 Net Configuration Assistant

To launch the assistant on Linux, run the netca shell script, located in the

$ORACLE_HOME/bin directory

Exercise 2-4: Use the DBCA to Create a Database In this exercise

you will create a database listener (if one does not exist already) and then create a

database to be called ocp11g using the DBCA, on either Windows or Linux There is

no significant difference between platforms The illustrations that follow happen to

be from Windows

1 Launch the Net Configuration Assistant The radio button for Listener

Configuration will be selected

2 Click NEXT three times If there is a message stating that a listener already exists,

you can exit the tool immediately by clicking CANCEL and FINISH, and proceed to

Step 3 Otherwise, click NEXT another four times to define the default listener,

and then FINISH to exit the tool

3 Launch the Database Configuration Assistant

4 On the DBCA Welcome dialog box, click NEXT

5 The next dialog box has radio buttons for

• Create a Database

• Configure Database Options

• Delete a Database

• Manage Templates

• Configure Automatic Storage

The second and third options will be grayed out, unless the DBCA detects an

existing database running off this Oracle Home Select the Create A Database radio button, and click NEXT

6 The Database Templates dialog box has radio buttons for selecting a template

on which to base the new database Select the Custom Database radio button,

as this will present all possible options Click NEXT

7 In the Database Identification dialog box, enter a global database name, and

a System Identifier (a SID), which will be used as the instance name These will default to the same thing, which is often what is wanted For this exercise,

enter ocp11g for both names Click NEXT

8 The Management Options dialog box has a check box for configuring the database with Enterprise Manager Select this Then there are radio buttons for either Grid Control or Database Control The Grid Control radio button will

be grayed out if the DBCA does not detect a Grid Control agent running on the machine Select Database Control There are check boxes for Enable Email Notifications and Enable Daily Backup; do not select these Click NEXT It is at this point that the DBCA will give an error if there is no listener available

9 The Database Credentials dialog box prompts for passwords for four users in the database: SYS (who owns the data dictionary), SYSTEM (used for most DBA work), DBSNMP (used for external monitoring), and SYSMAN (used by Enterprise Manager) Select the radio button for Use The Same Password For

All Accounts Enter oracle as the password, twice, and click NEXT

10 In the Security Settings dialog box, accept the default, which is 11g security,

and click NEXT

11 The Storage Options dialog box offers a choice between file system, ASM, or

raw devices Select File System, and click NEXT

12 The Database File Locations dialog box prompts for a root directory for the

database Select Use Database File Locations From Template Click the FILE LOCATION VARIABLES button to see where the database will be created It will be the OFA location ORACLE_BASE/oradata/DB_NAME Click NEXT

13 In the Recovery Configuration dialog box, accept the default configuration

for the flash recovery area (which will be 2GB in ORACLE_BASE/flash_ recovery_area) and do not enable archiving Click NEXT

14 In the Database Content dialog box, deselect all options except Enterprise

Manager Repository The others are not needed for this database and will increase the creation time Some options will be grayed out; this will be because they have not been installed into the Oracle Home Click the STANDARD DATABASE COMPONENTS button, and deselect these as well Don’t worry about a warning that the XML DB is used by other components Click NEXT

15 The Initialization Parameters dialog box has four tabs Leave the default

values, but examine all the tabs The Memory tab shows the memory that

will be allocated to the instance, based on a percentage of the main memory

detected The Sizing tab shows the database block size, defaulting to 8KB This

is the one thing that can never be changed after creation The Character Sets

tab shows the character set to be used within the database, which will have

a default value based on the operating system This can be very awkward to

change afterward The Connection Mode tab determines how user sessions

will be managed Click NEXT

16 The Database Storage dialog box shows, via a navigation tree on the left, the

files that will be created Navigate around this, and see the names and sizes of

the files These are usually nowhere near adequate for a production system but

will be fine for now Click NEXT

17 In the Creation Options dialog box, select the check boxes for Create

Database and Generate Database Creation Scripts Note the path for the

scripts; it will be ORACLE_BASE/admin/ocp11g/scripts Click FINISH

18 The Confirmation dialog box shows what the DBCA is about to do Click OK

19 The DBCA will generate the creation scripts (which should only take a few

minutes) Click OK, and the DBCA will create the database The illustration

that follows shows the progress dialog box Note the location of the DBCA

logs—ORACLE_BASE/cfgtoollogs/dbca/ocp11g—it may be necessary

to look at the logs if anything fails The creation will typically take fifteen to

forty minutes, depending on the machine

20 When the DBCA completes, it will present the dialog box shown in the

illustration that follows Take note of all the information given, in particular the URL given for database control:

https://jwacer.bplc.co.za:1158/em

The Scripts and Other Files Created by the DBCA

While the DBCA is creating the database, inspect the scripts generated They will be

in the directory ORACLE_BASE/admin/DB_NAME/scripts In the example that follow, which is from a Windows installation, the ORACLE_BASE is d:\oracle\app and the database name (the global name, without the domain suffix) is ocp11g, so the scripts are therefore in d:\oracle\app\admin\ocp11g\scripts Navigate to the appropriate directory, and study the files therein

The Instance Parameter File

The first file to consider is the instance parameter file, named init.ora This is a print of a typical init.ora file, as generated by the DBCA:

######################################################################

# Copyright (c) 1991, 2001, 2002 by Oracle Corporation

######################################################################

###########################################

# Cache and I/O

###########################################

db_block_size=8192

###########################################

# Cursors and Library Cache

###########################################

open_cursors=300

###########################################

# Database Identification

###########################################

db_domain=""

###########################################

# File Configuration

###########################################

control_files=("D:\oracle\app\oradata\ocp11g\control01.ctl",

"D:\oracle\app\oradata\ocp11g\control02.ctl",

"D:\oracle\app\oradata\ocp11g\control03.ctl")

db_recovery_file_dest=D:\oracle\app\flash_recovery_area

db_recovery_file_dest_size=2147483648

###########################################

# Job Queues

###########################################

job_queue_processes=10

###########################################

# Miscellaneous

###########################################

compatible=11.1.0.0.0

diagnostic_dest=D:\oracle\app

###########################################

# NLS

###########################################

nls_language="ENGLISH"

nls_territory="UNITED KINGDOM"

###########################################

# Processes and Sessions

###########################################

processes=150

###########################################

# SGA Memory

###########################################

sga_target=318767104

###########################################

# Security and Auditing

###########################################

audit_file_dest=D:\oracle\app\admin\ocp11g\adump

audit_trail=db

remote_login_passwordfile=EXCLUSIVE

###########################################

# Shared Server

###########################################

dispatchers="(PROTOCOL=TCP) (SERVICE=ocp11gXDB)"

###########################################

# Sort, Hash Joins, Bitmap Indexes

###########################################

pga_aggregate_target=105906176

###########################################

# System Managed Undo and Rollback Segments

###########################################

undo_management=AUTO

undo_tablespace=UNDOTBS1

Any line beginning with a # symbol is a comment and can be ignored There are

about 300 parameters, but the file generated by the DBCA sets only a few Most of

these are covered in detail in later chapters Two parameters to emphasize at this point

are DB_BLOCK_SIZE and CONTROL_FILES DB_BLOCK_SIZE determines the size of

the buffers in the database buffer cache When the instance is instructed to create a

database, this size will also be used to format the datafiles that make up the SYSTEM

and SYSAUX tablespaces It can never be changed after database creation CONTROL_

FILES is the pointer that allows the instance to find all the multiplexed copies of the