Re: Add connection active, idle time to pg_stat_activity

Hi,

On 2022-07-21 18:22:51 +0200, Sergey Dudoladov wrote:
> From b5298301a3f5223bd78c519ddcddbd1bec9cf000 Mon Sep 17 00:00:00 2001
> From: Sergey Dudoladov <sergey(dot)dudoladov(at)gmail(dot)com>
> Date: Wed, 20 Apr 2022 23:47:37 +0200
> Subject: [PATCH] pg_stat_activity: add 'total_active_time' and
> 'total_idle_in_transaction_time'
>
> catversion bump because of the change in the contents of pg_stat_activity
>
> Author: Sergey Dudoladov, based on the initial version by Rafia Sabih
>
> Reviewed-by: Aleksander Alekseev, Bertrand Drouvot, and Atsushi Torikoshi
>
> Discussion: https://www.postgresql.org/message-id/flat/CA%2BFpmFcJF0vwi-SWW0wYO-c-FbhyawLq4tCpRDCJJ8Bq%3Dja-gA%40mail.gmail.com

Isn't this patch breaking pg_stat_database? You removed
pgstat_count_conn_active_time() etc and the declaration for pgStatActiveTime /
pgStatTransactionIdleTime (but left the definition in pgstat_database.c), but
didn't replace it with anything afaics.

Separately from that, I'm a bit worried about starting to add accumulative
counters to pg_stat_activity. It's already gotten hard to use interactively
due to the number of columns - and why stop with the columns you suggest? Why
not show e.g. the total number of reads/writes, tuples inserted / deleted,
etc. as well?

I wonder if we shouldn't add a pg_stat_session or such for per-connection
counters that show not the current state, but accumulated per-session state.

Greetings,

Andres Freund