Connection Mode: a shortcut to improve database performance

I. Shared Server mode. The Shared Server mode is also called the multi-thread server mode. In this mode, the Oracle database allows multiple user processes to share very few server processes. Therefore, the number of concurrent users can be greatly increased. If the dedicated server mode is used, each user process

I. Shared Server mode. The Shared Server mode is also called the multi-thread server mode. In this mode, the Oracle database allows multiple user processes to share very few server processes. Therefore, the number of concurrent users can be greatly increased. If the dedicated server mode is used, each user process

I. Shared Server mode.

The Shared Server mode is also called the multi-thread server mode. In this mode, the Oracle database allows multiple user processes to share very few server processes. Therefore, the number of concurrent users can be greatly increased. If the dedicated server mode is used, each user's process needs its own dedicated server process when connecting to the database. That is to say, the client process corresponds to the server process one by one.

In the Shared Server mode, multiple users can share one server process. That is to say, the client process and the server process are many-to-one. This is mainly implemented through the scheduling program. The scheduler directs multiple database access Session requests to a shared queue. A idle server process in the server process sharing pool obtains a request from the queue in sequence. That is to say, a small server process sharing pool can provide services for a large number of clients.

The advantages and disadvantages of shared servers can be summarized in two sentences. The advantage is that the client process is many-to-one, increasing the number of users supported by the database. The disadvantage is that each user shares a process, which affects the user's database access performance.

Specifically, you can select the Shared Server mode in the following scenarios.

1. There are many front-end clients.

When a large number of users need to connect to the database and need to effectively use available system resources, they need to consider using the Shared Server mode. Specifically, network application software, such as the ERP system, is currently used in Client/Server mode. On the one hand, because of the large number of users, on the other hand, enterprises have limited funds, so they purchase General servers. These servers are subject to some hardware restrictions, such as database systems and front-end application servers using a uniform server. Therefore, databases are often required to make full use of hardware resources to reduce conflicts between the two.

In this case, the Shared Server mode is usually used, which is suitable.

2. The server memory limit is relatively large.

In Shared Server mode, when the number of connected users increases, the memory usage will not increase much. Because they share a server process. Therefore, from this perspective, the Shared Server mode can reduce memory usage. However, in dedicated server mode, memory usage is almost proportional to the number of users.

Therefore, if you deploy an Oracle database on some old servers, the upgrade of the memory on the main board is limited. Therefore, in order to get a good database performance, the Shared Server mode is usually used. In this way, the number of users who access the database at the same time increases, and the memory will not have much impact. Can greatly reduce the memory pressure.

3. Some specific features require the Shared Server mode.

Although the Shared Server mode and dedicated server mode are common in most cases, most of the functions of the Oracle database system are supported. However, some specific functions still need to be enabled by the database administrator in the Shared Server mode. Typical examples include connection sharing, connection centralization, and Server Load balancer for Oracle database servers. They can only run in shared mode.

Server Load balancer is used to implement multi-host database sharing in a cluster environment to ensure high availability of applications. At the same time, it can automatically achieve parallel processing and load balancing. It can also achieve Fault Tolerance and Non-breakpoint recovery in the case of database faults. Therefore, in some application scenarios with high performance and stability requirements, such as banks, Server Load balancer technology is often used. In this case, the database administrator needs to consider using the Shared Server mode When configuring the database.