What is the typical maximum number of database connections for Oracle running on Windows server?

In order to handle a database connection, a separate Oracle process is required, which may require up to 2 MB of memory. Normally an Oracle installation limits the number of concurrent connections based on the available memory and CPU configuration.

For example, let's say you have 50 customer accounts on the database with a maximum of 100 concurrent connections per account. If every account in average uses only 25% = 25 connections, the total average number would be 1250 connections. That means 2500 MB only for storing connection specific data. There is also processor time needed for context switching.

By setting limits on concurrent connections, you can ensure your transactions get through, and that some very active customer accounts don’t start to block your database server's resources. The number of connections is limited by the sessions parameter and your licensing. The sessions parameter controls the total number of connections including the Oracle background processes.

Adding more RAM to the server using a 64-bit Windows platform is a good idea, since you don’t have to spend a lot, even adding 16 GB of memory.

For detailed information of how configurations perform on realistic workload scenarios, read the Oracle E-Business Suite Standard Benchmark. Typically they have a large number of connections.