Oracle database creates two types of server processes to handle user requests shared and dedicated connections. The dedicated server process that serves the request of a single user. The second server process is a shared server that services multiple users.
When a user connects to the Oracle instance, it creates a process termed as Oracle SID where SID identifies a database on a system. The SID is dedicated to only one database and does not allow any other database with the same SID. These dedicated server connections require a lot of memory resource and often, the database servers fall short of memory as the connection remains idle. This slows down the process.
Dedicated server connection is desirable for administrative works or batch jobs where the user needs plenty of resources.
Most of the dedicated server connections are not active until such time that the user comes up with a new request. This not only eats up resources but blocks up another user to come up with their requests. A
shared server, on the other hand, works out to be more efficient. Instead of a one to one connection, it has one to multiple connections. It also scales efficiently allowing connections to multiple users at one single time.