Set the number of oracle connections

Oracle is one of the representatives of enterprise-level databases and is widely used in data storage and processing in various industries. In the era of big data and cloud computing, database stability and performance have become a very important topic. When using Oracle database, managing the number of connections is a very important aspect. This article will introduce how to set the number of connections in Oracle to improve the performance and stability of the database.

1. Why do you need to manage the number of connections?

In Oracle, each connection occupies memory and has a limit on the maximum number of connections. When the number of connections reaches the maximum limit, new connection requests will be rejected. When there are too many connections, resources such as system memory and CPU will be exhausted, leading to database performance degradation or even database crash. Therefore, managing the number of connections is an important guarantee for database stability and performance.

2. How to set the number of Oracle connections

1. Query the current number of connections

In Oracle, you can use the following SQL statement to query the current number of connections:

SELECT COUNT(*) FROM v$session;

2. Set the maximum number of connections

You can modify the maximum number of connections in Oracle through the following SQL statement:

ALTER SYSTEM SET PROCESSES=<MAX_CONNS> SCOPE=SPFILE;

where MAX_CONNS is the number of configurable maximum connections. The SCOPE parameter specifies the setting range, and SPFILE means that the set value will be written to SPFILE, which can make the setting effective permanently.

3. Set the maximum resource usage for each application connection number

Use the following SQL to set the maximum resource usage for each application connection number:

ALTER SYSTEM SET PGA_AGGREGATE_TARGET=<MAX_PGA_TARGET_SIZE> SCOPE=BOTH;

Where MAX_PGA_TARGET_SIZE is an integer value representing the maximum PGA memory (MB) obtained per session.

4. Set the connection pool size

In Oracle, you can create a connection pool to manage connections and thereby control the number of connections. A connection pool is a set of preconfigured connections available for use by applications. A connection pool consists of multiple connection fragments established with the database, and each connection fragment is regarded as a virtual connection.

You can use the following SQL statement to set the size of the connection pool:

ALTER SYSTEM SET SHARED_SERVERS=<POOL_SIZE> SCOPE=SPFILE;

where POOL_SIZE is the configurable connection pool size (that is, the number of virtual connections), and SPFILE indicates that the set value will be written SPFILE ensures the persistence of the settings.

3. How to judge whether there are too many connections?

1. Query the current number of connections:

Use the following SQL statement to query the current number of connections:

SELECT COUNT(*) FROM v$session;

2. Monitor the number of connections:

Can be used Various performance monitoring tools such as Enterprise Manager, AWR, Statspack, etc. to track the number of database connections. These tools can create reports to help identify excessive connections.

3. Operating system monitoring:

Through the operating system monitoring program, you can check the number of database processes, as well as the CPU and public memory occupied by Oracle-related processes. If there are too many processes and the CPU and memory load is high, it means there may be too many connections.

4. How to optimize the number of Oracle connections?

1. Use connection pool:

The connection pool is a pre-configured connection collection, which can optimize the performance of the connection, thus reducing the number of connections.

2. Use the connection manager:

Use the connection manager to limit the number of connections to better manage system resources. For example, configure connection timeouts so that idle connections are reused rather than reserved.

3. Optimize applications:

Optimizing applications can reduce the number of connections. For example, the same application requesting the same resource may be executed on the same connection, which can reduce the number of connections.

4. Monitor the number of connections:

Knowing the real-time number of connections can help quickly avoid system crashes. Therefore, you can use monitoring tools to monitor the performance of the number of connections, so that when the number of connections exceeds the safety threshold, you can take timely measures.

In short, managing the number of Oracle connections is a very important aspect, especially for large and high-performance enterprise-level database applications. By setting the maximum number of connections, managing connection pools, monitoring the number of connections, and optimizing applications, you can better manage and ensure the stability and performance of the Oracle database.

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