Re: pgsql: pg_stat_activity: show NULL stmt start time for walsenders

On 2020-Jan-07, Alvaro Herrera wrote:

> pg_stat_activity: show NULL stmt start time for walsenders
>
> Returning a non-NULL time is pointless, sinc a walsender is not a
> process that would be running normal transactions anyway, but the code
> was unintentionally exposing the process start time intermittently,
> which was not only bogus but it also confused monitoring systems looking
> for idle transactions. Fix by avoiding all updates in walsenders.
>
> Backpatch to 11, where walsenders started appearing in pg_stat_activity.

So I misidentified things; it's not commit be87b70b6117 (pg11) that put
auxiliary processes in pg_stat_activity, but fc70a4b0df38 (pg10). So I
applied it back to pg10 also. (I did verify that walsenders appear with
a xact_time in pg_stat_activity in pg10 before this patch, and not
afterwards.)

We're still computing useless xact start timestamps in branches 9.4 -
9.6, but I don't think we care. (If we do care, then we probably also
care about xact *stop* time ... but meh.)

Thanks

--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services