Database connection pooling is a technique used to improve the performance and scalability of applications that need to connect to a database.
In a typical scenario, when an application needs to connect to a database, it creates a new connection object, establishes a connection with the database, executes the desired queries or operations, and then closes the connection.
However, establishing a new database connection for every request can be costly and time-consuming. This is where connection pooling comes in.
Connection pooling creates a pool of pre-established connections to the database that can be reused by multiple client applications. Instead of creating a new connection for every request, the application retrieves a connection from the pool, uses it for its operations, and then returns it to the pool for reuse by other clients.
By reusing connections, the overhead of creating and closing connections is reduced, and the overall performance of the application is improved. Connection pooling also helps in managing the limited resources of the database server, as it can limit the number of active connections based on the configured pool size.
There are typically two types of connection pooling – physical connection pooling and logical connection pooling.
In physical connection pooling, the actual connection objects are reused. The pool maintains a set of available connections that are ready to be used by the client applications. When a client requests a connection, it is allocated an available connection from the pool, or a new connection is created if the pool is empty.
In logical connection pooling, the connections are not actually reused, but the underlying connection resources are shared. Each client application still gets a separate logical connection, but they share the same physical connection to the database. This helps in reducing the overhead of creating and closing connections, as well as managing the limited resources of the database server.
Overall, database connection pooling is an effective technique for improving the performance and scalability of applications that need to connect to a database. It reduces the overhead of creating and closing connections, improves the utilization of database server resources, and helps in managing the limited connection resources.