How to set up memory in oracle

Oracle is a widely used relational database management system, and its powerful performance and stability are widely recognized by the public. However, for beginners, how to correctly set up Oracle's memory is not an easy task. This article aims to introduce how to correctly set up memory in Oracle to improve database performance.

In Oracle, memory management includes SGA and PGA. SGA refers to the shared memory area, which is accessible to all users. PGA refers to process private memory, and only the corresponding process can access it. When setting up Oracle memory, consider the size of SGA and PGA respectively to meet the operating needs of the database.

First, we need to confirm the physical memory size of the server to ensure that the system has enough memory for Oracle to use. If there is insufficient memory, database performance will decrease and may even cause the database to crash.

Secondly, we need to determine the size of the SGA. The size of SGA should be adjusted according to the actual situation to ensure that the system has enough memory for the database. SGA consists of the following parts:

1. Database Buffer Cache: caches frequently used data blocks in the database. The cache size should be set to half of the physical memory.
2. Shared Pool: Cache SQL statements and shared memory. The cache size should be set to 1/4 of the physical memory.
3. Java Pool: Cache Java objects and Java Native code. The cache size should be set to 1/10 of physical memory.
4. Large Pool: Cache Oracle's internal structures, such as shared server processes, etc. The cache size should be adjusted as needed.

After determining the size of SGA, we can configure SGA through the following steps:

1. Use the vi /etc/sysctl.conf command to open the system configuration file.
2. Add the following parameters in the file:

kernel.shmall = 2097152
kernel.shmmax = 536870912

Among them, the kernel.shmall parameter specifies all Total shared memory segment size (in pages), the kernel.shmmax parameter specifies the maximum size of a single shared memory segment. Here, we set the total size of all shared memory segments to 2GB, and the maximum size of a single shared memory segment to 512MB. These parameters can be adjusted appropriately as needed.

3. Save the file and exit.
4. Run the sysctl -p command to make the configuration take effect.
5. Use the vi $ORACLE_HOME/network/admin/listener.ora command to open the Oracle client listener configuration file.
6. Add the following parameters in the file:

(SID_DESC =
(SID_NAME = oracle)
(ORACLE_HOME = /opt/oracle/product/11.2.0/ dbhome_1)
(PROGRAM = /opt/oracle/product/11.2.0/dbhome_1/bin/oracle)
(ENVS = 'LD_LIBRARY_PATH=/opt/oracle/product/11.2.0/dbhome_1/lib')
)

Among them, the SID_NAME parameter specifies the name of the database instance, the ORACLE_HOME parameter specifies the path to the Oracle installation directory, the PROGRAM parameter specifies the path to the Oracle program, and the ENVS parameter specifies the path to the Oracle runtime environment. .

7. Save the file and exit.

Finally, we need to determine the size of the PGA. The size of the PGA should be adjusted according to the actual situation to ensure that the system has enough memory for the process. The size of the PGA can be set by following these steps:

1. Use the ALTER SYSTEM command in the Oracle client to set the PGA_AGGREGATE_TARGET parameter to the appropriate size.

For example, ALTER SYSTEM SET PGA_AGGREGATE_TARGET=500M;

Among them, 500M means setting the size of PGA to 500MB.

2. Save changes and exit.

After setting the appropriate SGA and PGA sizes, we can start the Oracle database and test its performance. If the performance of the database is improved, it means that we have successfully set up Oracle's memory.

In summary, correctly setting Oracle's memory is crucial to improving database performance. When setting the memory, we need to consider the physical memory size of the server, the size of the SGA, and the size of the PGA, and adjust them appropriately. Through correct memory configuration, we can improve the operating efficiency of Oracle and ensure the safe and stable operation of the database.

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