Introduction
In the world of databases, standby databases are used to provide high availability and disaster recovery options. In certain situations, you may need to convert a standby database to a primary database. This can happen when the primary database fails or when you need to perform maintenance on the primary database. In this article, we will discuss how to convert a standby database to a primary database.
Step-by-Step Guide
Step 1: Check the State of the Standby Database
Before converting the standby database to the primary database, you need to check the state of the standby database. You can do this by running the following command:
SELECT DATABASE_ROLE FROM V$DATABASE;
If the output shows “PHYSICAL STANDBY,” then the database is in standby mode. If the output shows “PRIMARY,” then the database is already a primary database.
Step 2: Stop Redo Apply
To convert the standby database to the primary database, you need to stop redo apply. You can do this by running the following command:
ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;
This command will stop the redo apply process on the standby database.
Step 3: Activate the Standby Database
To activate the standby database, you need to run the following command:
ALTER DATABASE ACTIVATE PHYSICAL STANDBY DATABASE;
This command will activate the standby database and make it the primary database.
Step 4: Open the Database
After activating the standby database, you need to open the database using the following command:
ALTER DATABASE OPEN;
This command will open the database and make it available for use as the primary database.
Step 5: Disable Redo Transport
To prevent the original primary database from receiving redo data from the new primary database, you need to disable redo transport using the following command:
ALTER SYSTEM SWITCH LOGFILE;
This command will switch the log file and disable redo transport.
Step 6: Update TNS Entries
You need to update the TNS entries on all client machines that are using the database. The TNS entries should point to the new primary database.
Step 7: Verify the Conversion
To verify that the conversion was successful, you need to check the state of the database using the following command:
SELECT DATABASE_ROLE FROM V$DATABASE;
The output should show “PRIMARY,” indicating that the database is now a primary database.
Frequently Asked Questions
Here are some frequently asked questions related to converting a standby database to a primary database:
Q: Why would I need to convert a standby database to a primary database?
A: You may need to convert a standby database to a primary database if the original primary database fails or if you need to perform maintenance on the primary database.
Q: Can I convert a standby database to a primary database without stopping the original primary database?
A: No, you need to stop the original primary database before you can convert the standby database to a primary database.
Q: Can I convert a physical standby database to a logical standby database?
A: Yes, you can convert a physical standby database to a logical standby database using the following command: ALTER DATABASE CONVERT TO LOGICAL STANDBY;
Q: Can I convert a logical standby database to a physical standby database?
A: Yes, you can convert a logical standby database to a physical standby database using the following command: ALTER DATABASE CONVERT TO PHYSICAL STANDBY;
Q: What are the risks of converting a standby database to a primary database?
A: There is a risk of data loss if the original primary database fails before the conversion is complete. You should always make sure that you have a backup of the original primary database before converting a standby database to a primary database.
Conclusion
Converting a standby database to a primary database can be a useful technique for maintaining high availability and disaster recovery options. By following the steps outlined in this article, you can easily convert a standby database to a primary database in 2023. Remember to always make sure that you have a backup of your original primary database before making any changes.
