[pgpool-hackers: 3864] Re: Proposal: add connection count to pcp_proc_info and show pool_process

[Tatsuo Ishii]

> While writing a blog:
> https://pgsqlpgpool.blogspot.com/2020/12/timeouts-in-pgpool-ii-connections.html
> 
> I noticed that there's no metrics to know how many times connections
> from client have been made to a Pgpool-II process in pcp_proc_info and
> show pool_process. So I would like to propose to add that metrics to
> the commands. This would be useful to know how many times clients
> connect to Pgpool-II before they hit child_max_connections.

After thinking more I would like to propose to add following metrix.

- how many times clients connected to this pgpool process.

  proposed name: client_connection_count

- last time when frontend connected to this pgpool process.
  (or NULL is not connected yet)

  proposed name: client_connection_time

- last time when frontend disconnected to this pgpool process.
  (or NULL is not disconnected yet)

  proposed name: client_disconnection_time

- last time when pgpool connected to backend for this connection pool
  (or NULL is not connected yet)

  proposed name: backend_connection_time

- last time when pgpool disconnected to backend for this connection pool
  (or NULL is not disconnected yet)

  proposed name: backend_disconnection_time

- process status. possible values:

  WAIT_FOR_CONNECTION: waiting for connection from client
  IDLE: idle (not in transaction)
  IDLE_IN_TRANSACTION: idle (in transaction)
  SELECT: and other command executing

  proposed name: status