Oracle Certification: Learn to use DBCA to clone a database

DBCA is a tool that allows you to configure, manage, and create databases. During the initial database installation process, if you select "CreateADatabaseoption", the tool starts and runs. You can create a template-based database or import a new template from the previous example. Many administrators and

DBCA is a tool that allows you to configure, manage, and create databases. During initial Database installation, if you choose "Create A Database option", this tool will be started and run. You can create a template-based database or import a new template from the previous example. Many administrators and

DBCA is a tool that allows you to configure, manage, and create databases. During initial Database installation, if you choose "Create A Database option", this tool will be started and run. You can create a template-based database or import a new template from the previous example.

Many administrators do not know that you can enter the dbca environment by typing DBCA in the command line. Once the tool is started, you can create a new database, configure the INIT. ORA option of the database, delete an existing database, or manage the database template. These database templates are similar to those generated during installation (such as General Purpose, Data Warehouse, and Transaction Processing ).

During the installation process, an alert dialog box appears asking if you want to save your template. You can click "No" or manually define your database during installation. The DBCA tool can check database settings and generate a template based on the current operating system, and even selectively output the current data. This feature makes it an excellent tool for transferring a database to another machine or embedding a database into other valuable products.

The DBCA tool stores templates in a file with the. dbc extension. A. dbc file contains the init. ora parameter, location data file, log file, and a list of control files in XML format in the database. If you choose to include your database data, this tool will also generate a file with the extension. dbj, that is, a ZIP compressed file containing the image of your data file. Some users will think of creating a backup of all these settings to avoid the need to re-create a database on a new machine.

Many variables allow DBCA to install files in proper paths for Oracle software, such as {ORACLE_BASE} and {DB_NAME }. Because these are simple XML, you can use a diff function to quickly view the differences between these templates. For example, the difference between General Purpose and Data Warehouse database templates is that the Data Warehouse template of Oracle 9i 9.2.0.0:

TEMP tablespace is less than 1 M.

The init. ora parameters include:

Star_transformation_enabled is activated.

Pga_aggregate_target is compared in.

Query_rewrite_enabled is activated.

Db_file_multiblock_read_count is double.

Sort_area_size is double.

Hash_area_size is not set.

Db_cache_size is relatively small.

For the Transaction Processing template, the difference is:

The Oracle OLAP option is not activated.

The init. ora parameters include:

Db_block_size is half.

Undo_retention is relatively small.

Pga_aggregate_target is relatively small.

Db_file_multiblock_read_count is half.

Hash_join_enabled is disabled.

Db_cache_size is relatively large.

You do not need to create a CWMLITE tablespace (because the OLAP option has been disabled ).

EXAMPLE and SYSTEM tablespaces are relatively small.

TEMP tablespace is double the size.

When you use the DBCA tool to output data from the database, DBCA generates a file with the. dfj extension, that is, a ZIP compressed file containing the source image of each data file. This means that the data is secure during the transfer process. However, these files are not well documented and supported by EXP and IMP. Similarly, most of these images are directly written to the disk, rather than using SQL to write data similar to IMP.

(Source: Registration Network)

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