Expose connection_id access

[r33s3n6]

Description:
Users may need to terminate long-running queries by executing KILL <connection_id> in another connection, which requires access to the connection_id. While this ID can be obtained using SELECT CONNECTION_ID();, the server actually provides the connection_id during the handshake phase—we simply ignore it.

Would it be possible to store the connection_id in connection_state_data and expose a getter in any_connection for easier access?

Looking forward to your feedback on this proposal. Thanks!

[anarthal]

This definitely makes sense.