Why is a connection pool needed? What is a handshake when connecting to a database?

A connection pool is needed for efficient management of database connections. Creating a new connection is an expensive operation in terms of time and resources, so the pool maintains a set of open connections that are reused when executing queries. This significantly reduces delays and increases application performance, especially with a large number of parallel requests.

Handshake when connecting to a database is the process of establishing a connection between the client and the database server. During the handshake, parameters are exchanged: user authentication, protocol negotiation, session parameter setup. Only after a successful handshake can the client make requests to the database.

Example: when connecting to PostgreSQL, the client sends an authentication request, the server responds with an authentication method call, the client confirms, after which the connection is considered established.