Are Ado.net (2.0+) Connection Pools pre Application Domain or per Process

Question

I'm trying to understand the pooling theory w.r.t. to interactions between ADO.NET and SQL Server much better and haven't found the definitive answer. I have always assumed per process but it's just occurred to me that it could be per AppDomain.

Any in depth references would also be appreciated.

Answer 1

Connection pools are a complicated beast in that they are created in several differing scopes. According to SQL Server Connection Pooling on MSDN:

Connections are pooled per process, per application domain, per connection string and when integrated security is used, per Windows identity. Connection strings must also be an exact match; keywords supplied in a different order for the same connection will be pooled separately.

This means that you could have several connection pools within the same application based on how and where the connection is made.