DSNless Connections

The availability of DSNless connections means that your site can interface with any number of data sources (usually databases) without the need for ODBC (System DSN), by building the connection string(s) within your application code.

In fact, this type of connection is slightly more efficient than using a DSN, because using a DSN means that each database connection requires a registry lookup. This registry lookup is not overly expensive, but it does add up when you have a number of concurrent users (more than 10 concurrent connections using a DSN begins to cause an overhead).