What is SQL connection pooling in an ASP.NET Core application?

ADO.NET connection pooling reuses physical database connections instead of creating a new network/database session for every Open operation.

SqlConnection objects should normally be opened late and disposed promptly. Disposing usually returns the physical connection to the pool rather than closing the underlying network connection permanently.

Pools are separated by connection-string and identity-related characteristics. Connection leaks or long-running operations can exhaust the pool and cause application requests to wait or time out.