Muhammad Nadeem Chaudhry's Blog

DBCA to Create a Database

Posted in Uncategorized by Muhammad Nadeem Chaudhry on October 8, 2010

Starting DBCA

To launch DBCA on the Windows operating system use the following procedure:

1. Log onto your computer as a member of the administrative group that is authorized to install Oracle software and create and run the database.

2. To launch DBCA on a Windows operating system select the following: Start > Programs > Oracle – home_name > Configuration and Migration Tools > Database Configuration Assistant

To launch the DBCA on a UNIX, or as another method on a Windows operating system, enter the following at a command prompt: dbca which is typically found in $ORACLE_HOME/bin. The Welcome page appears.

3. Click Next to continue.

Using DBCA to Create a Database

Select Create a Database on the DBCA Operations page to begin a wizard that enables Oracle DBA to configure and create a database. During the interview, Oracle DBA are asked for your input on the following:

Database Templates

Database Identification

Management Options

Database Credentials

Storage Options

Database File Locations

Recovery Configuration

Database Content

Initialization Parameters

Database Storage

Creation Options

Note that most pages of the wizard provide a default setting that Oracle DBA can accept. To accept all the default parameters, Oracle DBA can click Finish at any step. Database Templates

This page enables Oracle DBA to select the type of database Oracle DBA want to create. By default, Oracle Corporation ships pre-defined templates. There are templates for Data Warehouse, General Purpose, and Transaction Processing databases. The templates contain settings optimized for workload. Click Show Details to see the configuration for each type of database. Choose the template suited to the type of workload your database will support. If Oracle DBA are not sure, select the default General Purpose template. For more complex environments, Oracle DBA may want to select the Custom Database option. This will result in a more extensive interview and it will take longer to create your database, since a database creation script must be run.

Database Identification

Enter the Global Database Name, in the form database_name.domain_name and SID (Oracle system identifier). The SID defaults to the database name and uniquely identifies the instance that runs the database.

Management Options

Use this page to set up your database so it can be managed with Oracle Enterprise Manager, which provides web-based management tools for individual databases, as well as central management tools for managing your entire Oracle environment. To use Enterprise Manager, check Configure the Database with Enterprise Manager. If the Oracle Management Agent has been installed on your host computer, then you are given the option of selecting central management by selecting Use Grid Control for Database Management. If you select this type of management, you must also indicate which management service to use in the drop-down menu. Otherwise, select Use Database Control for Database Management to manage your database locally. If you choose this option, you can additionally Enable Email Notifications, for Oracle to email you alerts regarding potential problems, and Enable Daily Backup. Click Help for more information about these options.

Database Credentials

In this page, you specify the passwords for the administrative accounts such as SYS and SYSTEM. To use the same password for all accounts, specify Use the Same Password for All Accounts and enter the password. Otherwise, specify Use Different Passwords and specify passwords individually. Storage Options

Specify the type of storage mechanism you would like your database to use. For more information, refer to “Installation Choices” earlier in this chapter. Database File Locations

In this page, Oracle DBA specify the Oracle home and directory path in which to install the Oracle software. Choose one of the following:

Use Database File Locations from Template—Selecting this option instructs the DBCA to use the directory information as specified in the template. Even if Oracle DBA choose this option, Oracle DBA will have an opportunity later to make modifications to database filenames and locations.

Use Common Location for All Database Files—This option requires Oracle DBA to specify a new directory for the Oracle home. All the database files will be created in this location. Even if Oracle DBA choose this option, Oracle DBA will have an opportunity later to make modifications to database filenames and locations.

Use Oracle-Managed Files—Select this option to eliminate the need for you, the DBA, to directly manage operating system files comprising an Oracle database. You specify default location called a database area for all your files. Oracle thereafter automatically creates and deletes files in this location as required. You also have the option to create multiple copies of your redo and online log files by Selecting this option enables you to delegate the complete management of database files to the database. Oracle DBA no longer need to specify the filenames, location, or their sizes.

Recovery Configuration

When Oracle DBA create a new database, it is important to configure the database so you can recover your data in the event of a system failure. Use this page to specify a flash recovery area and to enable archiving.

To specify a backup and recovery area, choose Specify Flash Recovery Area and specify its directory location and size. You can use variables to identify some standard locations. To review or add additional locations, click File Location Variables at the bottom of the page.

By checking Enable Archiving, you can enable archiving. This includes archiving database redo logs, which can be used to recover a database. Selecting this option is the same as enabling Archive Log Mode in Oracle Enterprise Manager or running the database in ARCHIVELOG mode. You can accept the default archive mode settings or change them by selecting Edit Archive Mode Parameters Oracle recommends you select Enable Archiving. Selecting this option provides better protection for your database in the case of software or hardware failure. If Oracle DBA do not select this option now, Oracle DBA can set up archive log mode later.

Database Content

In the Sample Schemas property page, check Sample Schemas if Oracle DBA want to include the Sample Schemas (EXAMPLE) tablespace in your database. The Sample Schemas provide a common platform for examples. Oracle books and educational materials contain examples based upon the Sample Schemas. Oracle recommends they be included in your database. In the Custom Scripts property page, you can specify one or more SQL scripts to run after your database is created. This is useful for performing post-installation tasks, such as loading custom schemas. To specify scripts, check Run the following scripts. Note that if you choose to run scripts after installation, your scripts must include a connect string that identifies the database. Click Help for more information. Otherwise to run no script, accept the default No scripts to run.

Initialization Parameters

The links on this page provide access to pages that enable you change default initialization parameter settings. These parameters fall into the following categories:



Character Sets

Connection Mode

Memory Use this page to set the initialization parameters that control how the database manages its memory usage. Oracle DBA can choose from one of two approaches to memory management:

Typical—requires little configuration, and allocates memory as a percentage of total overall physical system memory. To use this method, select Typical and enter a percentage value. Click Show Memory Distribution to see how much memory the Assistant assigns to the System Global Area (SGA) and the Program Global Area

Custom—requires more configuration, but gives Oracle DBA more control over how the database uses system memory. This option is meant for more experienced database administrators. Oracle DBA can directly specify memory sizes for the SGA and PGA and their sub-structures, such as the shared pool and buffer cache. To use this method, click Custom. To allocate specific amounts of memory to SGA and PGA, select Automatic. To customize how the SGA memory is distributed among the SGA memory substructures, select Manual and enter specific values for each SGA component. For a complete description of these memory areas, click Help. Sizing In this property page, Oracle DBA specify the smallest block size and the maximum number of operating system user processes that can simultaneously connect to the database.

To specify block size, enter the size in bytes or accept the default. Oracle database data is stored in these blocks. One data block corresponds to a specific number of bytes of physical space on disk. While using pre-defined templates, this field is not enabled since the database will be created with the default block size of 8KB. But while using the custom option, you can change block size. Selecting a block size other than the default 8 KB value requires advanced knowledge and should only be done when absolutely required.

To specify maximum number of processes that can simultaneously connect to the database, enter the number or accept the default. The value should be 6 or greater. This value should allow for all background processes, such as locks and parallel execution processes. The default value for this parameter is 150 which is good enough for many environments.

Character Sets Use this page to define the character sets used by your database. Character sets are the encoding schemes used to display characters on your computer screen. Choosing a character set determines what languages can be represented in the database.

For Database Character Set, select from one of the following options:

Use the Default–Select this option if Oracle DBA need to support only the language currently used by the operating system for all your database users and your database applications.

Use Unicode (AL32UTF8)–Select this option if you need to support multiple languages for your database users and your database applications.

Choose from the list of character sets–Select this option if Oracle DBA want the Oracle Database to use a character set other than the default character set used by the operating system.

The national character set is an alternate character set that enables you to store Unicode characters in a database that does not have a Unicode database character set. Another reason for choosing a national character set is that programming in the national character set might be easier. Select the National Character Set from the drop-down menu or accept the default.

information such as day and month abbreviations, default sorting sequence for character data, and writing direction (left or right). Select the default language from the drop-down menu or accept the default.

The Default Date Format determines the convention for displaying the hour, day, month, and year. For example in the United Kingdom, the date format is DD-MM-YYYY. Select the format from the drop-down menu or accept the default. Connection Mode Use this page to select the database mode. Oracle DBA can run the database in dedicated server mode or shared server mode.

In Dedicated Server Mode, there is a dedicated server process for each user process. Select this option when the number of total clients is expected to be small, or when database clients will make persistent, long-running requests to the database.

In Shared Server Mode, several client connections share a database-allocated pool of resources. Use this mode when a large number of users need to connect to the database. It is also useful when database memory is limited and for better performance, since you can have more client connections to the database than in dedicated server mode with the same memory. If Oracle DBA choose shared server mode, you must also indicate the number of server processes you want to create when an instance is started up. For more information about setting this parameter, click Help.

Database Storage

A tree listing shows you the storage structure of your database (control files, datafiles, redo log groups, and so forth). If you are not satisfied with the storage structure or parameters you can make changes. You can create a new object with Create and delete existing objects with Delete.

Note that if Oracle DBA selected one of the preconfigured templates for a database, you cannot add or remove control files, datafiles or rollback segments.

Creation Options

Oracle DBA have the option of creating your database at this time, or saving the database definition as a template to use at another time, or both.

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