About Logging for flashback Database and guaranteed Restore Points daily translation--20121120

Source: Internet
Author: User
The logging for flashback Database and guaranteed restore points is based upon

Capturing images of datafile blocks before changes are

Can is used to return the datafiles to their previous state when a flashback
The DATABASE command is executed.

The log and guaranteed repair point for the flashback database is based on the captured block mirroring before the changes, so these mirrors

The data file can be returned to its previous state when the Flashback database command is executed.

The chief differences between normal flashback logging and logging for guaranteed
Restore points are related to after blocks are logged and whether the logs can be
deleted in response to spaces pressure in the flash recovery area. These differences
affect spaces usage for logs and database performance.

The biggest difference between a normal flashback log and a log for a guaranteed point is all about when a block generates a log. Log

Whether it can be removed from the space pressure in the flashback zone. These differences affect the use of space for logging and database performance.

Whether to enable logging for flashback database, use guaranteed restore points, or
Both depends upon your recoverability goals, and the implications in performance and
In the spaces usage for the features, separately and when used together.

For flash database to allow logging, use a guaranteed fix point, or both depending on the target you can restore,

And for the impact of these functions on performance and space use, individual and functional effects are used together.

Guaranteed Restore Points and Flash Recovery area spaces Usage
When you create a guaranteed restore point, with or without enabling full flashback
Database logging, your must monitor the space available into your flash recovery area.
No file in the flash recovery the???? eligible for deletion if it's required to satisfy the
Guarantee. Thus, retention of flashback logs and other files required to satisfy the
Guarantee, as-as-files required to satisfy your backup retention policy, can cause
The Flash recovery area to fill completely.

Guaranteed repair point and flash back area space use

When you create a guaranteed fix point, there are or do not allow all to flash back to the database log, you must monitor in the Flash back area

Free space. In the flash-back zone there is no file that conforms to the deletion if it is required to meet the guaranteed fix point situation. That way, flash back.

The duration of the log and other documents are required to meet the assurance point, in order to meet your backup period of the policy of the file can cause flash back

The area is fully filled.

Caution:if no files are eligible for deletion from the flash recovery
Area because of the requirements imposed by your retention policy
And the guaranteed restore point, then the database behaves as if it
Has encountered a disk full condition. In many circumstances, this
Causes your database to halt. The "when" was not Available in the
Flash Recovery area ' on page 3-21 for more information on the effects
of a full flash recovery area.

Warning: If the flash-back zone does not have file compliance deletion because of the requirement to be defined by the term policy and the guaranteed fix point,

Then the database works if it encounters a full disk situation. In many cases, this will lead to your database

Hangs.

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.