oracle modify parameters

Oracle modification parameters

Oracle database is one of the most popular databases in the world. In order to ensure its efficient and stable operation, administrators often need to adjust some key parameters. This article will introduce how to modify parameters in the Oracle database to improve the performance and reliability of the database.

1. Check the database parameters

Before modifying the database parameters, we need to check the current database parameters and understand their meaning and configuration. You can run the following command to view:

SELECT name, value, isdefault, description 
FROM v$parameter 
ORDER BY name;

This command will display the current parameter settings, default values, description information and whether it is the default value of the database. Among them, name is the parameter name, value is the value of the current parameter setting, isdefault indicates whether it is the default value, and description is the description information of the parameter.

2. Modify database parameters

1. Manually modify parameters

To modify parameters manually, you can use the ALTER SYSTEM command. The syntax of this command is as follows:

ALTER SYSTEM SET 参数名称=新值 [SCOPE=内部修饰符];

The parameter name indicates the parameter name to be modified, and the new value indicates the modified parameter value. SCOPE is an optional SESSION, SID, or BOTH that specifies which dimension the modification will affect.

For example, the following command will modify the database sga_max_size parameter to 8192MB:

ALTER SYSTEM SET sga_max_size=8192M SCOPE=SPFILE;

2. Modify the parameters in the PFILE file

The same is true for modifying the parameters in the PFILE file Common methods. Oracle database will configure the database according to the parameters in the PFILE or SPFILE file when it is started. Modifying the PFILE file requires manually restarting the database after modification, while modifying the SPFILE file requires using the following command:

CREATE PFILE='<pfile路径>' FROM SPFILE;

Once the SPFILE file is modified, the database must be restarted for the parameters to take effect. You can use the following command to modify parameters in SPFILE:

ALTER SYSTEM SET 参数名称=新值;

For example, the following command will modify the database sga_max_size parameter to 8192MB:

ALTER SYSTEM SET sga_max_size=8192M;

3. Settings of common parameters

Understand common parameters Parameter setting is very important for database administrators. The following are some common Oracle parameters and their meanings:

1. sga_max_size: Specifies the maximum size of SGA;
2. sga_target: Specifies the target size of SGA;
3. pga_aggregate_target: Specify the target size of the PGA;
4. db_cache_size: Specify the database cache size;
5. shared_pool_size: Specify the shared pool size;
6. processes: Specify the number of user processes that can run simultaneously;
7. sessions: Specify the number of users who can connect to the database at the same time;
8. undo_retention: Specify the transaction rollback data retention time;

4. Notes

You need to pay attention to the following when modifying Oracle database parameters:

1. You need to back up the current parameter settings before modifying parameters so that you can roll back if necessary;
2. You need to consider when modifying parameters to the system resources of the server, such as memory, CPU, etc.;
3. It is recommended to conduct a comprehensive test on the database before modifying parameters to ensure the correctness and reliability of the new parameters;
4. Required when modifying parameters First understand its meaning and usage to avoid unnecessary impact on the database system.

In short, modifications to Oracle database parameters need to be carried out according to specific circumstances and require profound database technology and experience. This article describes how to modify parameters in Oracle Database to improve database performance and reliability. You need to pay attention to various precautions when modifying parameters to effectively optimize the performance and stability of the database.

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