Different types of standby database in oracle data guard

In oracle data guard configuration, you need to setup one or more additional databases beside the primary database. These additional databases are called standby database. Up to nice standby database can be created for one primary database.

Using a backup of primary database you can set up standby database and then you can made standby database as part of data guard configuration. Once you configured standby database, data guard automatically maintains standby database by transmitting redo log from the primary database and then applying redo to the standby database.

A standby database can be of three types.

1)Physical Standby Database: A physical standby database is an identical copy of the primary database. The disk structures are also identical with primary database. It is kept synchronized with the primary database by Redo Apply- which means the redo data is received from the primary database and then redo is applied to the physical standby database.

Note that as of Oracle Database 11g release 1 (11.1), a physical standby database can receive and apply redo while it is open for read-only access. You can use physical standby database for query and reporting purpose along with data protection.

2)Logical Standby Database: A logical standby database is the same logical information of the primary database. The physical data structure need not to be same on the standby database. It is kept synchronized with the primary database by SQL Apply- which means the redo data is received from the primary database, transforms redo data into SQL statements and at last executes the SQL statements on the standby database.

You can use logical standby database for query and reporting purpose along with data protection. Also you have to facility to upgrade oracle database software and patch sets along with data protection with help of logical standby database.

3)Snapshot Standby Database: A snapshot standby database is a convertible copy of the physical standby database but the difference from the physical or logical standby database is, the redo data that it received does not apply into it. The redo is applied whenever it is converted back to the physical standby database. You can play with the snapshot standby database and while converting to physical standby database from snapshot standby database these local updates are discarded.

Note that in case of snapshot standby database, the time needed to perform a role transition is directly proportional to the amount of redo data that needs to be applied.

Comments

  1. AnonymousAugust 14, 2021 at 12:35 PM

    This comment has been removed by the author.

    ReplyDelete
  2. AnonymousAugust 14, 2021 at 12:42 PM

    As you have mentioned in your article that in oracle data guard configuration, we need to setup one or more additional databases beside the primary database, it is informative for us. Thanks for sharing!
    Also if you are looking for web hosting services, you can choose Japan VPS Hosting Plans. Japan VPS Hosting will help to grow your business.

    ReplyDelete

Post a Comment

Popular posts from this blog

ORA-00923: FROM keyword not found where expected

Problem Symptom While performing a simple select statement it fails with error ORA-00923: FROM keyword not found where expected like below. SQL> select 48*1024*1024*1024 decimal from dual; select 48*1024*1024*1024 decimal from dual * ERROR at line 1: ORA-00923: FROM keyword not found where expected Cause of the problem The ORA-00923 can be caused by two different reasons. 1)Oracle itself expect FROM keyword in the position but it could not find any. Like below, SQL> select 48*1024 om dual; select 48*1024 om dual * ERROR at line 1: ORA-00923: FROM keyword not found where expected As no from keyword found so error arises. Oracle expected from in place of keyword dual. 2)The secong cause can sometimes mislead you. Like in case of SQL> select 48*1024*1024*1024 decimal from dual; select 48*1024*1024*1024 decimal from dual * ERROR at line 1: ORA-00923: FROM keyword not found where exp
Read more

How to make partitioning in Oracle more Quickly

As the table size grows and full table scans happens more frequently then there is no alternative than partitioning in oracle. Partition greatly enhance performance of a query. I will start my partitioning system simply with an example. In my database the following query took 30~35 seconds to complete. After partitioning the performance increased amazingly and it then took only 1 second. My query was, SELECT DISTINCT fs.type, fs.id , fs.pid, fs.cid , fs.cr_id, fs.created_date FROM summary fs where fs.id in (select fa.id from forms fa where fa.sar in (select la.sar from login la where la.login_id=1 and fa.created_date BETWEEN to_date('1-MAY-2008') AND to_date('21-SEP-2008') and fs.created_date BETWEEN to_date('1-MAY-2008') AND to_date('21-SEP-2008') ) )and mode=0; After seeing above query I decide to make range partition on column created_date both in summary table and forms table. Below is the list of procedur
Read more

Copy files between Unix and Windows with rcp

There are many third party tools by which you can copy files between windows and unix machine. Some common tools are winscp, SSHSecureShellClient etc. Instead of using any third party tool, you can use original unix and windows built-in tool to do the task. The RCP (Remote CoPy) is a standard UNIX tool and a Microsoft Windows 2000 tool that copies files/folder to and from computer running the RCP service. Before you can use the RCP tool from a Windows-based computer you must do something in your UNIX computer. you must turn on the RCP service and update the security files to allow the Windows-based computer to connect to your unix machine over this service. The following steps will help you. Step 01: Turn on RCP service on UNIX Host Turn on the RCP service on unix machine by using inetd: 1. Log on as root. 2. Edit the file /etc/Inetd.conf. 3. Uncomment the lines that start with shell and that start with exec. 4. Save the file. 5. Use ps -ef |grep inetd and determine inetd service p
Read more