A connection pool is a group of connection instances for one connection object. A connection instance is a representation of a physical connection to a data source. A connection pool library can contain multiple connection pools. The number of connection pools depends on the number of unique connections that the DTM instances use while running jobs.
You configure the Data Integration Service to run DTM instances in the Data Integration Service process or in separate DTM processes that run on local or remote nodes. Each Data Integration Service process or DTM process maintains its own connection pool library that all DTM instances running in the process can use. The number of connection pool libraries depends on the number of running Data Integration Service processes or DTM processes.
A connection instance can be active or idle. An active connection instance is a connection instance that a DTM instance is using to connect to a database. A DTM process or the Data Integration Service process can create an unlimited number of active connection instances.
An idle connection instance is a connection instance in a connection pool that is not in use. A connection pool retains idle connection instances based on the pooling properties that you configure for a database connection. You configure the minimum connections, the maximum connections, and the maximum idle connection time.